[LAA] Limit no-overlap check to at least one loop-invariant accesses.

Limit the logic added in https://github.com/llvm/llvm-project/pull/9230
to cases where either sink or source are loop-invariant, to avoid
compile-time increases. This is not needed for correctness.

I am working on follow-up changes to reduce the compile-time impact in
general to allow us to enable this again for any source/sink.

This should fix the compile-time regression introduced by this change:

* compile-time improvement with this change:
  https://llvm-compile-time-tracker.com/compare.php?from=4351787fb650da6d1bfb8d6e58753c90dcd4c418&to=b89010a2eb5f98494787c1c3b77f25208c59090c&stat=instructions:u

* compile-time improvement with original patch reverted on top of this
  change:
  https://llvm-compile-time-tracker.com/compare.php?from=b89010a2eb5f98494787c1c3b77f25208c59090c&to=19a1103fe68115cfd7d6472c6961f4fabe81a593&stat=instructions:u