Ruined portals can generate completely buried in netherrack

The Bug:

Ruined portals can generate completely buried in netherrack.

Here is an example:

Seed: 2178518626950662526
Coordinates: /execute in minecraft:overworld run tp @s -489.67 63.00 139.10 121.58 28.65

Steps to Reproduce:

1. Generate a world with the seed provided above and teleport to the given coordinates.
2. Look closely at the generation of the ruined portal.
3. Take note as to whether or not ruined portals can generate completely buried in netherrack.

Observed Behavior:

Ruined portals can generate completely buried in netherrack.

Expected Behavior:

Ruined portals would not be able to generate completely buried in netherrack.