feat(instance): use sbs api for block volumes

[Codelax]

b and block volume options are now the same as sbs. Instance b_ssd is no longer supported.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 75.00000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 70.79%. Comparing base (5bf53e0) to head (d7cb965).
Report is 455 commits behind head on master.

Files with missing lines	Patch %	Lines
...spaces/instance/v1/custom_server_create_builder.go	75.00%	5 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4435      +/-   ##
==========================================
- Coverage   75.45%   70.79%   -4.67%     
==========================================
  Files         202      299      +97     
  Lines       44323    66149   +21826     
==========================================
+ Hits        33444    46828   +13384     
- Misses       9653    17674    +8021     
- Partials     1226     1647     +421     

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