Windswept savannas in amplified worlds have the incorrect surface blocks

Shattered savannas will only generate stone on the surface in amplified worlds, when they should also be generating dirt, grass, and coarse dirt.

To reproduce, use the amplified world type, then use the seed 7897821280308200248 and run the following command:

/execute in minecraft:overworld run tp @p 774 317 -482