Fix incorrect check for local beatmap in `BeatmapDifficultyCache`
Fix incorrect check for local beatmap in `BeatmapDifficultyCache`

This was correct in the WIP branch I have, but pulled out alone (where
usages of `ToBeatmapInfo` still exist) it was not enough.

NeoAdonis/osu,peppy/osu,ppy/osu,NeoAdonis/osu,peppy/osu,ppy/osu,NeoAdonis/osu,smoogipoo/osu,smoogipoo/osu,smoogipooo/osu,peppy/osu,smoogipoo/osu,ppy/osu