Amplified worlds to not generate ocean varieties

When a world is set to `AMPLIFIED` mode, the various ocean biomes do not generate, only `ocean` and `deep_ocean`.

Steps to reproduce
1. Create a new world in creative, and set it to `AMPLIFIED` mode
2. Fly around a bit
3. The oceans that generate are not `lukewarm_ocean`, `cold_ocean`, etc. Only `ocean` and `deep_ocean`