This is the last step in removing cost-kind as a consideration in the basic class model for intrinsics. See D89461 for the start of that. Subsequent commits dealt with each of the special-case intrinsics that had customization here in the basic class. This should remove a barrier to retrying D87188 (canonicalization to the abs intrinsic).
The ARM and x86 cost diffs seen here are likely wrong because the target-specific overrides have their own bugs, but I hope this is less wrong - if something has a significant throughput cost, then it should have a significant size / blended cost too by default.
The only behavioral diff in current regression tests is shown in the x86 scatter-gather test (which is misplaced or broken because it runs the entire -O3 pipeline) - we unrolled less, and that's a good thing if I'm seeing it correctly.