Enable OTel by default

[kislaykishore]

Description

Use OTel for metrics by default. One can override the behavior to use OpenCensus instead by setting --enable-otel flag to false.

Perf:

Branch	File Size	Read BW	Write BW	RandRead BW	RandWrite BW
Master	0.25MiB	480.23MiB/s	1.28MiB/s	67.36MiB/s	1.24MiB/s
PR	0.25MiB	489.49MiB/s	1.21MiB/s	68.74MiB/s	1.32MiB/s
Master	48.828MiB	3535.15MiB/s	81.58MiB/s	1250.43MiB/s	82.85MiB/s
PR	48.828MiB	3428.55MiB/s	81.17MiB/s	1231.22MiB/s	81.53MiB/s
Master	976.562MiB	3420.17MiB/s	30.88MiB/s	412.77MiB/s	33.81MiB/s
PR	976.562MiB	3489.39MiB/s	33.64MiB/s	482.15MiB/s	32.29MiB/s

Link to the issue in case of a bug fix.

b/387898221

Testing details

1. Manual - yes
2. Unit tests - NA
3. Integration tests - Already tested vi existing CI tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.18%. Comparing base (c1f9198) to head (cad7f09).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2967      +/-   ##
==========================================
- Coverage   75.20%   75.18%   -0.02%     
==========================================
  Files         125      125              
  Lines       17734    17734              
==========================================
- Hits        13337    13334       -3     
- Misses       3833     3835       +2     
- Partials      564      565       +1     

Flag	Coverage Δ
unittests	75.18% <100.00%> (-0.02%)	⬇️

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