In the non-pooled case, `OnNewDrawableHitObject()` will be called
automatically on each new DHO via `Playfield.Add(DrawableHitObject)`.
In the pooled case, it will be called via `Playfield`'s implementation
of `GetPooledDrawableRepresentation(HitObject, DrawableHitObject)`.
Also removes a weird sizing application that seems to have no effect
(introduced in 27e63eb; compare removals for other taiko DHO types in
9d00e5b and 58bf288).