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

[Nikita Popov via llvm-commits]

nikic wrote:

Note that the commit message is taken from the PR description, so you'll want to add the information you added to the commit message there as well.

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