feat(api-logs): remove ProxyLogger from exports

[cjihrig]

Which problem is this PR solving?

ProxyLogger should be removed from the @opentelemetry/api-logs exports according to #6076.

Fixes #6076

Short description of the changes

This commit removes ProxyLogger from the @opentelemetry/api-logs exports.

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Test suite

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.16%. Comparing base (b99ca55) to head (dfb433c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6082   +/-   ##
=======================================
  Coverage   95.16%   95.16%           
=======================================
  Files         316      316           
  Lines        9207     9207           
  Branches     2075     2075           
=======================================
  Hits         8762     8762           
  Misses        445      445           

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[pichlermarc]

thanks!

[otelbot]

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