[clang] [llvm] [clang] Remove shell requirements from tests (PR #156905)

[Paul Kirth via llvm-commits]

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

LGTM. Windows has been opted out of all these tests thus far, so I don't see much reason to worry about the few that require symlinks. Probably confirm w Petr and Reid before landing though. 

https://github.com/llvm/llvm-project/pull/156905