[llvm] [LoopVectorize] Enable more early exit vectorisation tests (PR #117008)

[Florian Hahn via llvm-commits]

fhahn wrote:

> This works for me. Without looking deeper I cannot confirm if #120260 is valid but I figure there's no harm in landing all the fixes (and tests) in this PR and then #120260 can remove the one it improves upon when ready.

Yeah sounds good to me, I guess we can remove the extra checks again as part of #120260

https://github.com/llvm/llvm-project/pull/117008