[llvm] [LLVM] Do not require shell for some tests (PR #94595)

[Jay Foad via llvm-commits]

jayfoad wrote:

Hi @zmodem, I have just noticed that you have reverted some of these changes because of gnuwin32 failures. What did the failures look like? Is there a bot I can look at? I'd prefer to find a more precise way to disable them than `REQUIRES: shell` because these tests clearly do not require an external shell (at least not on all platforms).

https://github.com/llvm/llvm-project/pull/94595