[clang-tools-extra] [clang-tidy] Fix broken HeaderFilterRegex when read from config file (PR #133582)

[Carlos Galvez via cfe-commits]

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@@ -0,0 +1 @@
+HeaderFilterRegex: '.*'
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carlosgalvezp wrote:

It appears this use case was broken by this [patch](https://github.com/llvm/llvm-project/commit/0249554ee1ac49e6f1d93fa78a55971fc706f635),  @HerrCai0907  . 

There may be more things to fix.



https://github.com/llvm/llvm-project/pull/133582