impl(GCS+gRPC): more options for metrics exporter

[coryan]

Part of the work for #13998

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This change is 

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 93.80%. Comparing base (2bc2215) to head (6296ad4). Report is 4 commits behind head on main.

:exclamation: Current head 6296ad4 differs from pull request most recent head 2403eec. Consider uploading reports for the commit 2403eec to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #14238      +/-   ##
==========================================
+ Coverage   93.25%   93.80%   +0.55%     
==========================================
  Files        2210     2297      +87     
  Lines      192870   203706   +10836     
==========================================
+ Hits       179860   191094   +11234     
+ Misses      13010    12612     -398     

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