[Code Health] Include what you use, part 7

[marcalff]

Fixes #2054

Changes

Please provide a brief description of the changes here.

• Improve IWYU CI coverage to missing components (OTLP GRPC, prometheus, and opentracing-shim)
• Fix include-what-you-use warnings for the OTLP GRPC exporter
• Fix include-what-you-use warnings for the prometheus exporter
• Fix include-what-you-use warnings for the opentracing shim
• misc cleanup

With this 7th PR for include-what-you-use:

• The entire code base is covered in the include-what-you-use build
• The number of remaining issues is zero.

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

[netlify]

✅ Deploy Preview for opentelemetry-cpp-api-docs canceled.

Name	Link
🔨 Latest commit	9f38b77
🔍 Latest deploy log	https://app.netlify.com/sites/opentelemetry-cpp-api-docs/deploys/6785180edda1e30008e44eed

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.73%. Comparing base (d693e95) to head (9f38b77).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3238   +/-   ##
=======================================
  Coverage   87.73%   87.73%           
=======================================
  Files         198      198           
  Lines        6258     6258           
=======================================
  Hits         5490     5490           
  Misses        768      768           

Files with missing lines	Coverage Δ
sdk/src/logs/batch_log_record_processor.cc	82.90% <ø> (ø)
...metrics/export/periodic_exporting_metric_reader.cc	74.57% <ø> (ø)
sdk/src/trace/batch_span_processor.cc	87.84% <ø> (ø)

[marcalff]

@chusitoo

Totally optional, please take a look at the changes in the opentracing-shim if you have a chance.

[chusitoo]

@chusitoo

Totally optional, please take a look at the changes in the opentracing-shim if you have a chance.

@marcalff Nothing to report, thanks for the cleanup.