This reverts commit e2c3bbabb0.
This was superseded by #29871 which adds more crypto features with a
dedicated interface.
Since this commit was never in a stable release (merged during 3.2 dev),
we revert it to avoid having to deprecate it in favor of the Crypto API.
See https://github.com/godotengine/godot/pull/31187#issuecomment-523377965