[clang] [clang] [test] Skip a test that sets PATH= on Windows (PR #95096)

[Henry Linjamäki via cfe-commits]

linehill wrote:

Could the single test with the PATH manipulation be moved to a separate test file which is disabled on Windows? That way we could keep running the other tests on Windows.

https://github.com/llvm/llvm-project/pull/95096