Improve mutation test perf

[slang25]

Pull Request

These settings bring the runtime down to about 16 minutes for Polly.Core.Tests.

Details on the issue fix or feature implementation

Confirm the following

• I started this PR by branching from the head of the default branch
• I have targeted the PR to merge into the default branch
• I have included unit tests for the issue/feature
• I have successfully run a local build

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.22%. Comparing base (6cd95ba) to head (df1c1ff).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2520   +/-   ##
=======================================
  Coverage   94.22%   94.22%           
=======================================
  Files         311      311           
  Lines        7413     7413           
  Branches     1038     1038           
=======================================
  Hits         6985     6985           
  Misses        335      335           
  Partials       93       93           

Flag	Coverage Δ
linux	94.22% <ø> (ø)
macos	94.22% <ø> (ø)
windows	94.21% <ø> (ø)

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[martincostello]

For posterity, these are the numbers for different configurations at the time of writing:

Commit	Core	Extensions	Legacy	RateLimiting	Testing
6cd95ba (main)	29m 50s	5m 54s	10m 38s	4m 41s	4m 47s
df1c1ff (this PR)	19m 19s	2m 54s	6m 29s	2m 35s	2m 55s
c55e90a (#2522)	25m 10s	3m 16s	7m 30s	2m 33s	2m 50s

[github-actions]

Thanks for your contribution @slang25 - the changes from this pull request have been published as part of version 8.6.0 📦, which is now available from NuGet.org 🚀