[MC-11436] Vertical dispenser glitch

The vertical dispenser spawns entities to low

What I expected to happen was...:
When the dispenser spawns the entity, the mob appears ON the dispenser

What actually happened was...:
The entity go through the dispenser

Steps to Reproduce:
1. Put a vertical dispenser with mob egg in.
2. turn on the dispenser
3. The mob go through the dispenser