[llvm] [CI] Disable flang from Windows pre-commit tests (PR #93485)

[Vlad Serebrennikov via llvm-commits]

Endilll wrote:

> Flang tests are unstable on Windows pre-commit CI: https://discourse.llvm.org/t/flang-tests-are-extremely-slow-on-windows/78591/40

I think is should be removed from the description to avoid confusion. The current issues is OOM while building Flang on Windows, which is not the issue the Discourse thread was created for (worth a new thread?)

https://github.com/llvm/llvm-project/pull/93485