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`.
This is mainly to reach parity with how stable handles such cases for
skins specifically. It was brought to our attention after finding a skin
with a malformed `\[General]` tag which did not break further parsing of
the file on stable, but did on lazer.
Note that stable defaults to an "unknown" section for beatmaps, but
functionally I can't think of a regression case from changing this to a
"general" default.