[llvm] [SLP] Move more X86 tests to common directory (PR #111134)

[Alexey Bataev via llvm-commits]

alexey-bataev wrote:

> @alexey-bataev Since I am adding more tests, do you think classifying them by topics would be appropriate? (e.g. something like arithmetic, reduction, extractelement, insertelement, etc)

I think so

https://github.com/llvm/llvm-project/pull/111134