"wall_dispenser" dispenser traps can generate behind walls in trial chambers

Bedrock Edition repost of MC-270696.

"wall_dispenser" dispenser traps can generate behind walls in trial chambers, rendering them pointless.

Seed: -3451608330957216249
Coordinates 1: 91 -22 228
Coordinates 2: 623 7 205

Seed: -8147499510490594898
Coordinates: 867 -37 116

Steps to Reproduce:

1. Create a new world using the given seed.
2. Enter Spectator mode.
3. Teleport to one of the given coordinates.

Observed Results:
"wall_dispenser" dispenser traps can generate behind walls.

Expected Results:
"wall_dispenser" dispenser traps would not generate behind walls.