feat(api-usage): add environment variable to prevent API usage tracking.

[matthewelwell]

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Changes

Adds an environment variable which controls whether API usage data is tracked.

Closes #2580.

How did you test this code?

Ran the docker compose file locally with the following settings:

      USE_POSTGRES_FOR_ANALYTICS: 'true'
      ENABLE_API_USAGE_TRACKING: 'false'

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[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (16e6a28) 95.93% compared to head (f31eb1a) 18.04%.
Report is 4 commits behind head on main.

Files	Patch %	Lines
api/app/settings/common.py	66.66%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3386       +/-   ##
===========================================
- Coverage   95.93%   18.04%   -77.89%     
===========================================
  Files        1077      996       -81     
  Lines       32944    28721     -4223     
===========================================
- Hits        31606     5184    -26422     
- Misses       1338    23537    +22199     

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