Use standard list instead of bindable list
Use standard list instead of bindable list

No reason to use a bindable list there, as `CollectionChanged` was never
subscribed to.

peppy/osu,UselessToucan/osu,peppy/osu,NeoAdonis/osu,peppy/osu,ppy/osu,smoogipoo/osu,smoogipoo/osu,ppy/osu,NeoAdonis/osu,smoogipoo/osu,peppy/osu-new,NeoAdonis/osu,UselessToucan/osu,smoogipooo/osu,ppy/osu,UselessToucan/osu