[llvm] Revert "[SLP]Support revectorization of the previously vectorized scalars" (PR #134604)

[Alexander Kornienko via llvm-commits]

alexfh wrote:

> Agree, but it may cause some other unexpected side effects already, there are some patches on top of it already :(

Indeed, I see a commit-revert-reland chain of #132099 and a few other related commits in the last few days. Reverting that all is probably even messier than landing a fix forward here =(


https://github.com/llvm/llvm-project/pull/134604