perf: use queue instead of groups for parallel tests

[wellwelwel]

Closes #849.

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Tests to be added

• No tests with concurrency manually specified as zero.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.90%. Comparing base (5a8af21) to head (dde6d2c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #886      +/-   ##
==========================================
- Coverage   99.11%   98.90%   -0.22%     
==========================================
  Files          35       35              
  Lines        1814     1820       +6     
  Branches       10       13       +3     
==========================================
+ Hits         1798     1800       +2     
  Misses          8        8              
- Partials        8       12       +4     

Flag	Coverage Δ
linux	98.84% <100.00%> (-0.17%)	⬇️
osx	98.84% <100.00%> (-0.22%)	⬇️
windows	98.84% <100.00%> (-0.17%)	⬇️

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