[SLP]Fix PR87133: crash because of different altopcodes for cmps after reordering.

If the node has cmp instruction with 3 or more different but swappable
predicates, need to keep same kind of main/alternate opcodes to avoid
incorrect detection of opcodes after reordering. Reordering changes the
order and we may erroneously consider swappable opcodes as
non-compatible/alternate, which may lead to a later compiler crash.

Reviewers: RKSimon

Reviewed By: RKSimon

Pull Request: https://github.com/llvm/llvm-project/pull/87267