Disabling and enabling dimension datapack disables nether and end

1. Add testpack2 datapack and create world: 4 dims with overworld, custom:lol, end, nether
2. Verify this by doing `/execute in <tab>`
3. Disable pack and rejoin: 1 dim overworld
4. Enable pack and rejoin: 2 dims with overworld and custom:lol
5. Notice that the end and nether no longer exist

Datapack was sourced from https://github.com/RainWarrior/test/tree/sure