Closes https://github.com/ppy/osu/issues/31915.
Reproduction of aforementioned issue requires 1280x720 resolution, which
should also be a good way to confirm that this does anything.
To me this is also equal-parts-bugfix, equal-parts-code-quality PR,
because tell me: what on earth was this code ever doing at
`ComposeBlueprintContainer` level? Nudging by one playfield-space-unit
doesn't even *make sense* in something like taiko or mania.
Previously the slider path length would be snapped using the current
beat snap setting on *every* change of the slider path. As it turns out
this is unexpected behaviour in some situations (e.g. when reversing a
path, which is expected to preserve the previous duration, even though
the slider may be technically "unsnapped" at that point in time due to a
different beat snap setting being selected afterwards).