custom_hit_test hitboxes don't scale with the mob

Partner Rank: 3

Verification builds: 1.16.0.2
Regression builds: None (this component was introduced in 1.16)

Summary: Unlike collision_box which scales with the scale component, custom_hit_test hitboxes don't scale.

Impact: This would be fairly easy to work around with scale alone, but the same issue occurs with scale_by_age, which is impossible to work around. This causes a minor feature in an upcoming map to not work correctly.

Repro Steps:

1. Download and open the attached world
2. Enable debug hitboxes
3. Right-click the pig with carrots repeatedly

Expected Results: All hitboxes remain the same relative size.

Observed Results: The yellow custom custom_hit_test hitbox remains at a constant size as the pig grows.

Screenshots/Videos attached: Yes