Fix Flaky test port reservation

[jerbly]

We have flaky tests due to port collisions despite using port picker. There are race hazards due to parallel runs.

Solved with our own implementation of port reservation which also separates port selection for multiple binaries running at the same time.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.1%. Comparing base (f174ab4) to head (aac787c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/weaver_test_support/src/lib.rs	0.0%	11 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1463     +/-   ##
=======================================
- Coverage   82.2%   82.1%   -0.1%     
=======================================
  Files        125     126      +1     
  Lines      10241   10252     +11     
=======================================
  Hits        8423    8423             
- Misses      1818    1829     +11     

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