Split up beatmaps with different length on some difficulties for Length sorting #5390
Description
Describe the problem with the feature: It's nice to see that the Length sorting is already implemented on Lazer, but on its current state.. it feels wrong. Here's an example:
These two beatmaps have different length on some difficulties (luckily those difficulties are already sorted by length by themselves, otherwise they would not be ordered correctly by length inside the same beatmap: they keep the Difficulty sorting. Look at this image as example), and as you can see the beatmap below has difficulties with a lower length than the last difficulty of the beatmap above.
Proposal designs of the feature: The only idea that I have right now is to split up the beatmaps (like on stable) and put difficulties on their respective length range. It's an important design because it can also depend on #2547 for the possible design of a beatmap with a single difficulty.