[llvm] [ci] limit parallel windows compile jobs to 24 (PR #93329)

[Aaron Ballman via llvm-commits]

https://github.com/AaronBallman approved this pull request.

LGTM as far as the experiment goes, in case you want to land it to see if it solves the OOM issues immediately. We can explore other options in a follow-up if desired.

https://github.com/llvm/llvm-project/pull/93329