ci: Update permissions for workflow

[utpilla]

Changes

• Restrict workflow permissions even further by limiting the read only access to contents. Check the documentation for reference.
• Remove cron based trigger for CodeQL workflow since we are running the workflow for each commit.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.3%. Comparing base (6b5251f) to head (2807b7e).
Report is 2 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2923   +/-   ##
=====================================
  Coverage   81.3%   81.3%           
=====================================
  Files        126     126           
  Lines      24254   24254           
=====================================
  Hits       19736   19736           
  Misses      4518    4518           

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