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

[Aaron Ballman via llvm-commits]

AaronBallman wrote:

FWIW, I've also found I need to set LLVM_PARALLEL_LINK_JOBS to something low (like 2-4) unless building with lld. link.exe tends to be quite memory hungry as well, so maybe that's another option to experiment with here?

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