Remove Windows llvm 17 and 18 jobs from ci

[mcbarton]

Description

Please include a summary of changes, motivation and context for this PR.

We are unlikely to ever have Windows builds passing all tests building against llvm 17 and 18. After #463 is merged this PR should be merged, so we can remove the cache used up by these jobs. Keeping the llvm 19 build makes sure our Windows build doesn't break. With the freed up cache space I plan to replace these 2 Windows jobs with Ubuntu 24.04 x86 coverage, which is a good trade.

Fixes # (issue)

Type of change

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• Bug fix
• New feature
• Requires documentation updates

Testing

Please describe the test(s) that you added and ran to verify your changes.

Checklist

• I have read the contribution guide recently

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.15%. Comparing base (54c9482) to head (37a2340).
Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #464   +/-   ##
=======================================
  Coverage   71.15%   71.15%           
=======================================
  Files           9        9           
  Lines        3550     3550           
=======================================
  Hits         2526     2526           
  Misses       1024     1024