Mob spawning in only the end should speed up in low terrain similar to 1.17

As there are no changes to world generation in the end and also most of the terrain, in the end, is low down, it makes sense to keep the old mob spawning in the end. I think it works in the overworld as the new height limit and more terrain lower/higher does make finding mobs on mountains a bit slower but I don't think the end should go by the same rules. This change will also make enderman xp farms a good option again as in the 1.18 exp3, these farms are way too slow to be a fast option for xp unless you add lots more spawning spaces.

I don't think the nether should be changed back or overworld as the terrain in the nether can be very high or very low.