Refactory opentelemetry benchmarks

[cijothomas]

Separate into metrics and key values. We expect to add more such micro benchmarks to get good understanding of the overhead introduced in opentelemetry itself.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.0%. Comparing base (df12c2c) to head (d6cef71).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #1614   +/-   ##
=====================================
  Coverage   67.0%   67.0%           
=====================================
  Files        138     138           
  Lines      19515   19515           
=====================================
  Hits       13084   13084           
  Misses      6431    6431           

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