[SCEV] Handle `less` predicates for FoundPred = NE

Currently these predicates are ignored, yet their handling is
pretty simple. I could not find a single test where it would
actually change something, but it's only because isImpliedCondOperands
is not smart enough to prove it further on. Yet the situation when
we come there with `less` predicate is pretty common.

Differential Revision: https://reviews.llvm.org/D87890
Reviewed By: fhahn