[CODE HEALTH] Fix clang-tidy misc-use-internal-linkage warnings

[marcalff]

Fixes # (issue)

Changes

Please provide a brief description of the changes here.

• Fix clang-tidy misc-use-internal-linkage warnings.

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.07%. Comparing base (355bf9b) to head (369b404).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3918   +/-   ##
=======================================
  Coverage   90.07%   90.07%           
=======================================
  Files         226      226           
  Lines        7217     7217           
=======================================
  Hits         6500     6500           
  Misses        717      717           

Files with missing lines	Coverage Δ
exporters/ostream/src/metric_exporter.cc	91.55% <100.00%> (ø)
exporters/ostream/src/span_exporter.cc	88.55% <100.00%> (ø)
sdk/src/common/env_variables.cc	100.00% <100.00%> (ø)
...egation/base2_exponential_histogram_aggregation.cc	91.33% <100.00%> (ø)
...export/periodic_exporting_metric_reader_options.cc	100.00% <100.00%> (ø)

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