[AMDGPU] Avoid inserting noops during scheduling

Passes that are run after the post-RA scheduler may insert instructions like
waitcnt which eliminate the need for certain noops. After this patch the
scheduler is still aware of possible latency from hazards but noops will
not be inserted until the dedicated hazard recognizer pass is run.

Depends on D89753.

Reviewed By: foad

Differential Revision: https://reviews.llvm.org/D89754