[BUILD] Fix references to trace namespace to be fully qualified

[bogdandrutu]

Fixes #2417

[codecov]

Codecov Report

Merging #2422 (b65cd95) into main (064fef0) will not change coverage.
The diff coverage is 0.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2422   +/-   ##
=======================================
  Coverage   87.06%   87.06%           
=======================================
  Files         199      199           
  Lines        6079     6079           
=======================================
  Hits         5292     5292           
  Misses        787      787           

Files	Coverage Δ
...pentelemetry/sdk/metrics/exemplar/reservoir_cell.h	58.83% <0.00%> (ø)
...ude/opentelemetry/sdk/metrics/data/exemplar_data.h	0.00% <0.00%> (ø)

[lalitb]

Thanks

[marcalff]

Thanks for the fix.

[qinyeli]

@bogdandrutu Thanks for the fix!!
I noticed a similar issue in otlp_recordable/opentelemetry/exporters/otlp/otlp_recordable.h and opentelemetry/exporters/etw/etw_tracer.h as well. Can you help fix those as well?

bazel-out/aarch64-fastbuild/bin/external/io_opentelemetry_cpp/exporters/otlp/_virtual_includes/otlp_recordable/opentelemetry/exporters/otlp/otlp_recordable.h:51:18: error: 'opentelemetry::v1::exporter::trace::StatusCode' has not been declared
   51 |   void SetStatus(trace::StatusCode code, nostd::string_view description) noexcept override;
      |                  ^~~~~
bazel-out/aarch64-fastbuild/bin/external/io_opentelemetry_cpp/exporters/otlp/_virtual_includes/otlp_recordable/opentelemetry/exporters/otlp/otlp_recordable.h:51:8: error: 'void opentelemetry::v1::exporter::otlp::OtlpRecordable::SetStatus(int, opentelemetry::v1::nostd::string_view)' marked 'override', but does not override
   51 |   void SetStatus(trace::StatusCode code, nostd::string_view description) noexcept override;
      |        ^~~~~~~~~

I went through all "trace::" in the repository, and it seems that those not-fully-qualified namespace in api (eg) and those in .cc (eg) does not cause the same issue. However, I assume those in the .h files should be fixed.