Entity shadows ignore slabs and render on full blocks below instead

Short description:
Entity shadows are not correctly projected onto partial blocks such as slabs. Instead, the shadow passes through the slab and renders on the full block underneath.

Steps to reproduce:

1. Place a bottom slab above a full block.

2. Summon or spawn a mob (example: zombie) standing on the slab.

3. Look at the entity shadow in spectator mode for example.

Expected result:
The shadow should be projected onto the slab surface, matching the entity position.

Actual result:
The shadow ignores the slab collision surface and appears on the full block below, as if the slab was not considered a valid surface for shadow rendering.

Additional notes:
This becomes very visible entities or mobs standing on slabs, especially in custom builds using many non-full blocks.