[BugFix] Fix the bug of bitmap_to_binary/bitmap_to_base64 processing null (backport #45275)

[mergify]

Why I'm doing:

All the result for bitmap_to_string(null), bitmap_to_binary(null), bitmap_to_base64(null) should be null;

What I'm doing:

Before the pr:

mysql> select bitmap_to_binary(null);                                                                                                                                                                                                                                             
+------------------------------------------------+                                                                                                                                                                                                                                
| bitmap_to_binary(NULL)                         |                                                                                                                                                                                                                                
+------------------------------------------------+                                                                                                                                                                                                                                
| NULL                                           |                                                                                                                                                                                                                                
+------------------------------------------------+ 

mysql> select bitmap_to_binary(bitmap_from_string("abc"));                                                                                                                                                                                                                        
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| bitmap_to_binary(bitmap_from_string('abc'))                                              |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| 0x00                                                                                     |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
1 row in set (0.02 sec)

After the pr:

mysql> select bitmap_to_binary(null);                                                                                                                                                                                                                                             
+------------------------------------------------+                                                                                                                                                                                                                                
| bitmap_to_binary(NULL)                         |                                                                                                                                                                                                                                
+------------------------------------------------+                                                                                                                                                                                                                                
| NULL                                           |                                                                                                                                                                                                                                
+------------------------------------------------+ 

mysql> select bitmap_to_binary(bitmap_from_string("abc"));                                                                                                                                                                                                                        
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| bitmap_to_binary(bitmap_from_string('abc'))                                              |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| NULL                                                                                     |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 3.3
  • 3.2
  • 3.1
  • 3.0
  • 2.5

---

This is an automatic backport of pull request #45275 done by [Mergify](https://mergify.com). ## Why I'm doing:

All the result for bitmap_to_string(null), bitmap_to_binary(null), bitmap_to_base64(null) should be null;

What I'm doing:

Before the pr:

mysql> select bitmap_to_binary(null);                                                                                                                                                                                                                                             
+------------------------------------------------+                                                                                                                                                                                                                                
| bitmap_to_binary(NULL)                         |                                                                                                                                                                                                                                
+------------------------------------------------+                                                                                                                                                                                                                                
| NULL                                           |                                                                                                                                                                                                                                
+------------------------------------------------+ 

mysql> select bitmap_to_binary(bitmap_from_string("abc"));                                                                                                                                                                                                                        
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| bitmap_to_binary(bitmap_from_string('abc'))                                              |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| 0x00                                                                                     |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
1 row in set (0.02 sec)

After the pr:

mysql> select bitmap_to_binary(null);                                                                                                                                                                                                                                             
+------------------------------------------------+                                                                                                                                                                                                                                
| bitmap_to_binary(NULL)                         |                                                                                                                                                                                                                                
+------------------------------------------------+                                                                                                                                                                                                                                
| NULL                                           |                                                                                                                                                                                                                                
+------------------------------------------------+ 

mysql> select bitmap_to_binary(bitmap_from_string("abc"));                                                                                                                                                                                                                        
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| bitmap_to_binary(bitmap_from_string('abc'))                                              |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+                                                                                                                                                                                      
| NULL                                                                                     |                                                                                                                                                                                      
+------------------------------------------------------------------------------------------+

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
• This is a backport pr

[mergify]

Cherry-pick of 20a3136 has failed:

On branch mergify/bp/branch-2.5/pr-45275
Your branch is up to date with 'origin/branch-2.5'.

You are currently cherry-picking commit 20a3136336.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   test/sql/test_bitmap_functions/R/test_bitmap_to_base64
	new file:   test/sql/test_bitmap_functions/T/test_bitmap_to_base64

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   be/src/exprs/vectorized/bitmap_functions.cpp
	deleted by us:   test/sql/test_bitmap_functions/R/test_bitmap_binary
	deleted by us:   test/sql/test_bitmap_functions/T/test_bitmap_binary

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

@mergify[bot]: Backport conflict, please reslove the conflict and resubmit the pr