[llvm] [LoopUtils] Pre-commit test for follow-up metadata for loops (NFC) (PR #131337)

[Michael Kruse via llvm-commits]

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Meinersbur wrote:

This is a test for the LoopVectorizer (see [LoopVectorizeHints](https://github.com/llvm/llvm-project/blob/792a6f81198842352fa5213faf7ecad4b1d27ddd/llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h#L60)) to apply the correct metadata, so `Transforms/LoopVectorize`.

https://github.com/llvm/llvm-project/pull/131337