[clang-tools-extra] [clang-tidy][NFC] swap cppcoreguidelines-narrowing-conversions and bugprone-narrowing-conversions (PR #120245)

[Julian Schmidt via cfe-commits]

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5chmidti wrote:

Please change the header guard to use `bugprone` as the 'path' instead of `cppcoreguidelines`

https://github.com/llvm/llvm-project/pull/120245