[VPlan] Invert condition if needed when creating inner regions. (#132292)
As pointed out by @iamlouk in
https://github.com/llvm/llvm-project/pull/129402, the current code
doesn't handle latches with different successor orders correctly.
Introduce a `NOT`, if needed.
Depends on https://github.com/llvm/llvm-project/pull/129402
PR: https://github.com/llvm/llvm-project/pull/132292