Snow golem hitbox is not adjusted after being sheared

The Bug

After shearing a snow golem, its hitbox is not adjusted to the actual head of the mob.

Steps to Reproduce

• Obtain some shears and summon a snow golem.

  /summon minecraft:snow_golem ~ ~ ~ {NoAI:1b}
  

• Enable entity hitboxes. (F3 + B).
• Use the shears on the snow golem.
• Take note as to whether or not the snow golem's hitbox is shortened in height after being sheared.

Observed Behavior

Snow golems' hitboxes are not shortened in height after being sheared.

Expected Behavior

Snow golems' hitboxes would be shortened in height after being sheared.