[llvm] [LoopVectorize] Use new single string variant of reportVectorizationFailure (PR #120414)

[David Sherwood via llvm-commits]

david-arm wrote:

> LGTM thanks

Thanks for taking a look. It seems like I need to update my downstream format checking scripts because downstream they pass and upstream they fail. :(

https://github.com/llvm/llvm-project/pull/120414