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

[Michael Kruse via llvm-commits]

Meinersbur wrote:

I collected statistics some time ago: https://discourse.llvm.org/t/build-time-comparision/56024 (including for `/cgthreds1`). Usage may have grown since then.

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