[MC-224494] Regular dirt can generate naturally on the surface near pools

The bug

Dirt can generate naturally on the surface near pools, which is pointless because it ends up becoming grass anyways. This also occurs with lava pools.

Reproduction steps

Note that reproducing this bug seems to be dependent on the order in which chunks are loaded. Therefore you might have to adjust your view distance and don't directly teleport to affected placed. The original reporter used 16 chunk render distance.

Last updated for 21w17a

2021-04-29_17.34.27.png

Seed:
```
-5208210088792058538
```

Coordinates:
```
/teleport -12 76 -544
```

If you do not see dirt patches at the above location, try teleporting to the following location afterwards:

/execute in minecraft:overworld run tp @s -192.32 66.25 -644.35 -49.20 53.70