[llvm] [LV]: Ensure fairness when selecting epilogue VF. (PR #155547)

[Hassnaa Hamdi via llvm-commits]

hassnaaHamdi wrote:

> It looks like `LLVM.Transforms/LoopVectorize/AArch64/interleaving-reduction.ll` is failing in pre-commit, probably needs a rebase + test update?

It fails as expected, I tried to strip out the renaming to show you the difference of the logic. After you see the changes, I will update the file again.

https://github.com/llvm/llvm-project/pull/155547