CLI-1388: Deprecate source-git-tag

[danepowell]

Motivation

Fixes #1787
Fixes CLI-1388

Proposed changes

Deprecate --source-git-tag. If --destination-git-branch is set, use it for the same purpose.

Alternatives considered

Testing steps

1. Follow the contribution guide to set up your development environment or download a pre-built acli.phar for this PR.
2. Clear the kernel cache to pick up new and changed commands: ./bin/acli ckc
3. (add specific steps for this pr)

[github-actions]

Try the dev build for this PR: https://acquia-cli.s3.amazonaws.com/build/pr/1801/acli.phar

curl -OL https://acquia-cli.s3.amazonaws.com/build/pr/1801/acli.phar
chmod +x acli.phar

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.23%. Comparing base (93dcab1) to head (4bb29e7).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1801   +/-   ##
=========================================
  Coverage     92.23%   92.23%           
- Complexity     1817     1818    +1     
=========================================
  Files           121      121           
  Lines          6823     6825    +2     
=========================================
+ Hits           6293     6295    +2     
  Misses          530      530           

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