1cd69220ef only disabled snapping the
aforementioned nodes to distance grid for already-placed sliders.
`SliderPlacementBlueprint` has its own logic for placement, so the fix
needs to be mirrored there too.
Until now, these were haphazardly enforce inline in blueprint
implementations. The only thing stopping complete breakage is that
`EndPlacement` wasn't called (too much) from outside the blueprint,
leaving them responsible for their own placement.
By moving this conditional out of the provided paramters to
`EndPlacement`, it allows more flexible usage of that method externally.
Coming in a future PR.
The actual visual extension is only applied to `HitCircle`s (which does include slider
start / end), and should not be applied to spinners in the first place.
Addresses https://github.com/ppy/osu/discussions/22949.