People were deleting files they shouldn't, causing osu! to lose track of
where the real user files are.
For now let's just keep things simple and not let the users know that
some files got left behind. Usually the files which are left behind are
minimal and it should be fine to leave this up to the user.
Closes https://github.com/ppy/osu/issues/29505.
The more proper way to do this would be to address the underlying issue,
which is https://github.com/ppy/osu/issues/29546, but let's do this
locally for now.