fix(storage): respect GOOGLE_CLOUD_CPP_OPENTELEMETRY_TRACING

[dbolduc]

Fixes #13765

Same story as #13748. storage and bigtable do not call PopulateCommonOptions(), so we need to manually handle GOOGLE_CLOUD_CPP_OPENTELEMETRY_TRACING. They are the only two such libraries that need this manual works.

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This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.26%. Comparing base (95fce04) to head (9803b54).
Report is 32 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #13766   +/-   ##
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  Coverage   93.26%   93.26%           
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  Files        2229     2229           
  Lines      193104   193121   +17     
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+ Hits       180105   180121   +16     
- Misses      12999    13000    +1     

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