[verify-regalloc] Verify after allocation and before postOptimization

I've now hit several cases where a mistake in the regalloc main loop caused corrupt live intervals that didn't get caught until either the next verify or during post-optimization.  The later case is rather confusing and tends to lead one down false trails, so let's catch corruption before that.

GitOrigin-RevId: 13753808f4e990089bf34ff44474e85cc3e6e775
1 file changed