[EXAMPLES] Deprecated semantic conventions used

[marcalff]

Fixes #3890

Changes

Please provide a brief description of the changes here.

• In metrics_foo_library, use non deprecated semantic conventions as example
• In the grpc example, use proper rpc semantic conventions

This resolves deprecation warnings related to old semantic conventions.

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 90.06%. Comparing base (355bf9b) to head (ff0ce76).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3905      +/-   ##
==========================================
- Coverage   90.07%   90.06%   -0.01%     
==========================================
  Files         226      226              
  Lines        7217     7217              
==========================================
- Hits         6500     6499       -1     
- Misses        717      718       +1     

see 1 file with indirect coverage changes

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[marcalff]

Thanks @dbarker