Piglins only attack Wither Skeletons when in a group

The bug

Piglins are hostile towards Wither Skeletons and therefore should always attack them. However, Piglins only attack Wither Skeletons when they are in a group of at least two.

To reproduce

1. Spawn a Wither Skeleton
2. Spawn a Piglin
   → It will not attack
3. Spawn a second Piglin
   → Now they do attack