[clang] [clang-tools-extra] [clang-format] Fix leaking of host-level config into test environment (PR #206358)

[Björn Schäpers via cfe-commits]

https://github.com/HazardyKnusperkeks commented:

I don't see any harm on the clang-format file.

https://github.com/llvm/llvm-project/pull/206358