Mobs spawned by monster eggs don't despawn.

Steps to reproduce

1. Spawn a mob using a spawn egg.
2. Travel far enough away that the mob is outside of simulation distance.
3. Travel back to the mob

Expected result

The mob is gone.

Actual result

The mob is still there.

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So I was trying to make a witch farm and to figure out despawn mechanics. In my testing, I used a creeper spawn egg to test how far away I most be to have the farm work. I flew multiple chunks away (what would be more than enough to despawn a creeper) and came back to a still spawned creeper. This is back by how a cow that was near the creeper had despawned and the creeper had not. Please fix this. To other players please test this as well to confirm my suspicions.