[llvm] [LoopVectorize] Fix double-application of FindIV reduction expression in epilogue (PR #219362)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

@im-lunex is there a reason for closing the PR? 

Please also see https://llvm.org/docs/AIToolPolicy.html. 

Please also update the PR description to clearly and concisely describe the issue and how the patch fixes it.

You can drop things like  `added test..` which do not add any information 

https://github.com/llvm/llvm-project/pull/219362