[llvm] [LoadStoreVectorizer] Postprocess and merge equivalence classes (PR #114501)

[Michal Paszkowski via llvm-commits]

michalpaszkowski wrote:

@v-klochkov Reverting the change due to [a failure](https://lab.llvm.org/buildbot/#/builders/55/builds/4171). This may require some investigation. Here is the [reverting pull request](https://github.com/llvm/llvm-project/pull/119657).

https://github.com/llvm/llvm-project/pull/114501