Multiple Shulkers at same position create Shulker Bullets without hitting each other

Relates to:

• MC-83838

When multiple Shulkers are at the same spot (this can happen in Survival) and they start shooting, they hit each other. Unlike described in MC-83838 (fixed), the ShulkerBullets now stay where they spawned without moving at all (however their NBT data is not corrupted).

This is very likely caused by the fact that only ShulkerBullets with Motion entries that are not 0 can damage an entity, but as the ShulkerBullets are already at their destination, they do not have to move.