Removes CMS_TOKEN

[Salonichoudhary07]

Fixes #297

Summary

CMS_TOKEN was not being used at the backend.

Test Plan

• Wrote tests
• Tested locally
• Tested on staging
• Tested on production
• If adding or removing any environment variable:
  • update docs/ENV.md
  • update the environment variables for staging and production
• If changes in DB, update [DB schema] and BigQuery (staging and prod)

[codecov]

Codecov Report

Merging #305 (21dbb9b) into master (ef4f6ec) will decrease coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #305      +/-   ##
==========================================
- Coverage   97.01%   97.01%   -0.01%     
==========================================
  Files         147      147              
  Lines        2714     2713       -1     
==========================================
- Hits         2633     2632       -1     
  Misses         81       81              

Impacted Files	Coverage Δ
plio/settings.py	87.01% <ø> (-0.17%)	⬇️

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[deepansh96]

Minor changes