chore: Print Python traceback when POLARS_TIMEOUT_MS is exceeded

[orlp]

This will allow us to more easily find out what failed when a test times out.

To achieve this we have to eagerly grab a traceback every time enter_polars is called. This is quite a performance impact, but POLARS_TIMEOUT_MS is only a debugging tool.

[codecov]

Codecov Report

❌ Patch coverage is 22.85714% with 27 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.59%. Comparing base (9d8a77e) to head (75d2716).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-python/src/timeout.rs	23.07%	20 Missing ⚠️
crates/polars-python/src/utils.rs	22.22%	7 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #27657      +/-   ##
==========================================
+ Coverage   81.48%   81.59%   +0.10%     
==========================================
  Files        1840     1840              
  Lines      256109   256135      +26     
  Branches     3181     3181              
==========================================
+ Hits       208696   208981     +285     
+ Misses      46588    46328     -260     
- Partials      825      826       +1     

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