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

[Alexander Kornienko via llvm-commits]

alexfh wrote:

> This breaks Transforms/SLPVectorizer/X86/reordered-masked-loads.ll. Apparently, the test relies on some changes in #133091.

Ah, the test is quite fresh - added in https://github.com/llvm/llvm-project/commit/19aec007351394b552855120e6840537d8780e9d. @alexey-bataev can you take care of updating it after the revert or should I disable it with XFAIL or otherwise?

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