Vex no longer displays equipped player heads and skulls

Vexes have always supported displaying Player Heads when they are equipped in the head slot. While not available in survival, this option was available using commands or data packs, and has been used by map makers. However Vexes no longer display the Player Head, even when upgrading from an existing world where they were previously visible.

Steps to Reproduce:

• Open a world in 1.19.2 and summon a Vex wearing a Player Head using a command such as:
  • summon vex ~ ~2 ~ {PersistenceRequired:1b,NoAI:1b,ArmorItems:[{},{},{},\{id:"minecraft:player_head",Count:1b}]}
• Note that the Player Head is visible on the Vex.
• Save the world and upgrade to 22w45a. The Player Head is no longer visible, even though the item is still equipped.