Named wandering traders despawn

Even when named with a name tag, wandering traders despawn after their DespawnDelay nbt tag reaches 0, which is inconsistent with the endermite, a mob with a similar despawning system.

How to reproduce:

1. Rename a name tag in an anvil
2. Summon a wandering trader with DespawnDelay set to 500 (note that with just "/summon wandering_trader", DespawnDelay will be 0, which prevents the wandering trader from despawning
3. Use the name tag on the wandering trader

         →  After DespawnDelay reaches 0, the wandering trader despawns