Enhance code review instructions with additional checks

[harsha-simhadri]

Added additional code review checks regarding unit tests, dependencies, and build times.

[Copilot]

Pull request overview

Updates the repository’s code review guidance to include additional review checks beyond license headers, focusing on test coverage, dependency hygiene, and build-time impact.

Changes:

• Added checklist items to flag removed unit tests without strong justification.
• Added guidance to scrutinize newly introduced dependencies.
• Added a reminder to consider potential build time regressions, while retaining the license header check.

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[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.30%. Comparing base (b616aa3) to head (a7f6a67).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #866      +/-   ##
==========================================
- Coverage   90.45%   89.30%   -1.16%     
==========================================
  Files         442      442              
  Lines       83248    83248              
==========================================
- Hits        75301    74341     -960     
- Misses       7947     8907     +960     

Flag	Coverage Δ
miri	89.30% <ø> (-1.16%)	⬇️
unittests	89.14% <ø> (-1.28%)	⬇️

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see 38 files with indirect coverage changes

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