Add Fix for the Size-based containsRegion Heuristic

[Eric-Vin]

Description

This fixes the size-based fast path used in containsRegion. It previously triggered when tolerance is non-zero (but ignored tolerance) and was susceptible to small numerical errors. This fix disables it for cases with non-zero tolerance and adds a small fudge-factor to ensure the heuristic is robust to small numerical errors.

Issue Link

N/A

Checklist

• I have tested the changes locally via pytest and/or other means
• I have added or updated relevant documentation
• I have autoformatted the code with black and isort
• I have added test cases (if applicable)

Additional Notes

N/A

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.71%. Comparing base (d74f61c) to head (494a24d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #458      +/-   ##
==========================================
+ Coverage   89.64%   89.71%   +0.06%     
==========================================
  Files          48       48              
  Lines       13226    13226              
==========================================
+ Hits        11857    11866       +9     
+ Misses       1369     1360       -9     

Files with missing lines	Coverage Δ
src/scenic/core/regions.py	87.94% <100.00%> (+0.35%)	⬆️

... and 3 files with indirect coverage changes

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[dfremont]

Thanks Eric!