Skip migration for deleted dimensions post first migration in server

[Doc94]

Related to #13873 this PR with the help of @jpenilla try to manage the case where dimensions can be deleted of the server (post-migration to paper world structure).

Currently if you delete a dimension the server try to run a migration based in the changes what its not necesary, so we skip that logic and modify the later call to load worlds for manage to correctly regen that dimensions.

Know Issues.

• If you delete the overworld dimension you get a crash for the missing world_gen_settings.dat (in paper that file is in the dimension directories), in vanilla you can get the same crash but need delete the file from the global data directory in the world

Closes #13873

[davidmayr]

Isn't it possible to recreate the world_gen_settings.dat, like done in createNewWorldData if the overworld dimension missing? I don't think paper should fail this gracefully here, especially if this also happens when the server fails to fully create the world the first time it starts up (like when e.g. another server is running on the same port)

See an example of where this is a problem here: https://mclo.gs/rUXPi0V (This is not using your patch for world migration, but it should come to the same conclusion)

Sure, this can be easily fixed by users, although I think it shouldn't be a too difficult fix for something that will definitely happen to more people in the future

[Doc94]

Isn't it possible to recreate the world_gen_settings.dat, like done in createNewWorldData if the overworld dimension missing? I don't think paper should fail this gracefully here, especially if this also happens when the server fails to fully create the world the first time it starts up (like when e.g. another server is running on the same port)

See an example of where this is a problem here: mclo.gs/rUXPi0V (This is not using your patch for world migration, but it should come to the same conclusion)

Sure, this can be easily fixed by users, although I think it shouldn't be a too difficult fix for something that will definitely happen to more people in the future

This require maybe not remove the gen file when migration its done for use when remove in vanilla (in vanilla you can force this error too but require more steps)... but this PR is for another thing, if you can open an issue related to this.