Cherrypick #7998, #8011, #8010 into 1.70.x

[arjan-bal]

Original PRs:

• server: fix buffer release timing in processUnaryRPC #7998
• xdsclient: release lock before attempting to close underlying transport #8011
• github: Run deps workflow against base branch and add branch name suffixes for easier debuggability #8010

RELEASE NOTES:

• server: Free buffers holding raw data of request message as soon as parsing is finished in unary RPCs instead of waiting till the method handler returns. (server: fix buffer release timing in processUnaryRPC #7998)
• TBD (xdsclient: release lock before attempting to close underlying transport #8011)

[codecov]

Codecov Report

Attention: Patch coverage is 93.75000% with 1 line in your changes missing coverage. Please review.

Project coverage is 82.17%. Comparing base (54b3eb9) to head (5a06379).
Report is 1 commits behind head on v1.70.x.

Files with missing lines	Patch %	Lines
xds/internal/xdsclient/client_refcounted.go	87.50%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           v1.70.x    #8028      +/-   ##
===========================================
+ Coverage    82.02%   82.17%   +0.15%     
===========================================
  Files          384      384              
  Lines        38706    38718      +12     
===========================================
+ Hits         31748    31817      +69     
+ Misses        5637     5590      -47     
+ Partials      1321     1311      -10     

Files with missing lines	Coverage Δ
server.go	82.62% <100.00%> (+0.09%)	⬆️
xds/internal/xdsclient/client_refcounted.go	81.81% <87.50%> (-0.24%)	⬇️

... and 23 files with indirect coverage changes

[dfawley]

Please remember to N/A the release notes from the original PRs so these don't appear in the 1.71 relnotes too.