Closes https://github.com/ppy/osu/issues/20824.
Note that this will require a reimport of beatmaps as it is baked into the database. Probably not worth making a migration for at this point in time.
The editor doesn't currently propagate velocity to nested objects. We're
not yet sure whether it should or not. For now, let's just ignore nested
objects' `DifficultyControlPoints` for simplicity.
Note that this only affects osu! ruleset due to the pre-check on
`isOsuRuleset`.