Fix DrawableJudgement not always animating correctly on skin change
Fix DrawableJudgement not always animating correctly on skin change

If the skin is changed before gameplay has started (at the loading
screen) it is possible for a sequence of events to occur which results
in the animation not being played:

- `SkinReloadableDrawable` runs its BDL load (and calls `OnSkinChanged`
  once)
- User changes skin, triggering `DrawableJudgement`'s skin change
  handling (binding directly on the `SkinSource` locally)
- This will call `PrepareDrawables` and reinitialise the
  `SkinnableDrawable` child hierarchy, then immediately apply the
animations to it.
- The new `SkinnableDrawable` will then get the `SkinChanged` event and
  schedule a handler for it, which will run on its first Update call.
- Any added animations will be lost as a result.

Fixed by binding directly to the `SkinnableDrawable`'s `OnSkinChanged`.
This has the added bonus of not needing to reinitialise the child
hierarchy on skin change (which felt a bit weird in the first place).

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