[lld] Remove shell requirements from tests
These tests all pass inside the lit internal shell. A couple were marked
as requiring a shell to exclude them on Windows. Update those tests to
explicitly carve out Windows rather than any configuration that does not
provide the shell feature.
Towards #102700.
Reviewers: petrhosek, cmtice, mysterymath, MaskRay, ilovepi
Reviewed By: cmtice
Pull Request: https://github.com/llvm/llvm-project/pull/156510
