opentelemetry: Refactor tracing and metrics separately

[janardhanvissa]

RELEASE NOTE: This release refines the separation of metrics and tracing logic.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.41%. Comparing base (39f0e5a) to head (76e422a).
Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8063      +/-   ##
==========================================
+ Coverage   82.27%   82.41%   +0.13%     
==========================================
  Files         386      387       +1     
  Lines       39038    39057      +19     
==========================================
+ Hits        32120    32189      +69     
+ Misses       5590     5549      -41     
+ Partials     1328     1319       -9     

Files with missing lines	Coverage Δ
stats/opentelemetry/client_metrics.go	90.14% <100.00%> (+0.74%)	⬆️

... and 35 files with indirect coverage changes

[purnesh42H]

@janardhanvissa its not clear what is the intention of this refactor. The follow up from opentelemetry tracing API PR was to create separate interceptors for metrics and traces. Right now, single interceptor is handling both trace and metrics options. Once we have separate unary and stream interceptor each for tracing and metrics, we don't have to check for options disabled/enabled everytime.

[purnesh42H]

Please see this discussion https://github.com/grpc/grpc-go/pull/7852/files#r1909469701 and modify accordingly.