Stabilize test suite: fix flaky timing tests, and handle Windows reso…

[Dreamsorcerer]

…urce leaks (#11992)

(cherry picked from commit 32924e8)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.22%. Comparing base (47d045d) to head (daa78ca).
⚠️ Report is 1 commits behind head on 3.14.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             3.14   #12075      +/-   ##
==========================================
+ Coverage   97.23%   98.22%   +0.99%     
==========================================
  Files         128      128              
  Lines       45010    45018       +8     
  Branches     2439     2439              
==========================================
+ Hits        43766    44220     +454     
+ Misses        989      615     -374     
+ Partials      255      183      -72     

Flag	Coverage Δ
CI-GHA	98.10% <96.29%> (+0.86%)	⬆️
OS-Linux	97.86% <92.59%> (+0.62%)	⬆️
OS-Windows	95.55% <44.44%> (?)
OS-macOS	97.11% <77.77%> (?)
Py-3.10.11	96.64% <81.48%> (?)
Py-3.10.19	97.13% <92.59%> (?)
Py-3.11.14	97.37% <92.59%> (+0.13%)	⬆️
Py-3.11.9	96.89% <81.48%> (?)
Py-3.12.10	96.97% <77.77%> (?)
Py-3.12.12	97.46% <92.59%> (?)
Py-3.13.12	97.68% <92.59%> (?)
Py-3.14.3	97.64% <55.55%> (?)
Py-3.14.3t	96.74% <55.55%> (?)
Py-pypy3.11.13-7.3.20	96.89% <40.74%> (?)
VM-macos	97.11% <77.77%> (?)
VM-ubuntu	97.86% <92.59%> (+0.62%)	⬆️
VM-windows	95.55% <44.44%> (?)

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[codspeed-hq]

Merging this PR will not alter performance

✅ 59 untouched benchmarks

---

_{Comparing patchback/backports/3.14/32924e8fa4c9085dcbaf41b3b3c27fc773bfa213/pr-11992 (daa78ca) with 3.14 (47d045d)}