Trial chambers can generate exposed to the air

Bedrock Edition repost of MC-266446 (resolved as Won't Fix).

Comment by [Mojang] slicedlime

Improved in 1.20.5-pre1. Remaining cases are from carvers (not noise caves), and are considered Won't fix status.

Trial chambers can generate exposed to the air, relates to MCPE-146753.

Seed: 3317253191420042803
Coordinates: -1084 -1 584

Seed: 3317253191420042803
Coordinates 1: -1107 -8 599
Coordinates 2: -251 -14 -1666

Steps to Reproduce:

1. Create a new world using the given seed.
2. Teleport to the given coordinates.

Observed Results:
Trial chambers can generate exposed to the air.

Expected Results:
Trial chambers shouldn't generate exposed to the air.