[llvm] [InstCombine] Fold icmp eq/ne X, select(icmp pred X, P, C1, C2) to set membership (PR #226756)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw approved this pull request.

LGTM.

> also remove the Test plan part of the pr description

AI usage should be noted as per https://llvm.org/docs/AIToolPolicy.html

https://github.com/llvm/llvm-project/pull/226756