[clang-tools-extra] [clang-tools-extra] Remove 'REQUIRES: shell' from lit tests. (PR #156950)

[via cfe-commits]

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@@ -1,4 +1,4 @@
-// REQUIRES: shell
+// UNSUPPORTED: system-windows
----------------
cmtice wrote:

> Could you share info what you found (if any) so we would fix tests and enable them in the future?

Here are the log files from the failed runs (when I removed "REQUIRES: shell", before I added "UNSUPPORTED").

[bar.cpp.log](https://github.com/user-attachments/files/22217172/bar.cpp.log)
[clang-tidy-diff.cpp.log](https://github.com/user-attachments/files/22217173/clang-tidy-diff.cpp.log)
[vfsoverlay.cpp.log](https://github.com/user-attachments/files/22217174/vfsoverlay.cpp.log)


https://github.com/llvm/llvm-project/pull/156950