[llvm] [LoopRotate] Remove canRotateDeoptimizingLatchExit and multi-rotate (PR #162482)

[via llvm-commits]

annamthomas wrote:

@mark-sed  does not have commit access. He's asked me to push it for him. I'll enable auto-merge, which should push the changes once CI passes.

https://github.com/llvm/llvm-project/pull/162482