Truncate start time of juice stream nested objects

Intended as at least a partial solution to
https://github.com/ppy/osu/issues/26436. In testing, two of the three
replays from the issue are FCs with this change, and the third is
improved (and not fully fixed).

As it turns out, stable truncates the end time of sliders to integers:

    79addff0f5/osu!/GameplayElements/HitObjects/Osu/SliderOsu.cs#L1037

and the start time of all juice stream parts is also truncated to
integers:

    79addff0f5/osu!/GameplayElements/HitObjects/Fruits/SliderFruits.cs#L86-L166

This matters for replay playback when mappers push limits. For instance,
let's take one case from the issue. In one of the maps involved, there
was a juice-stream-ending fruit at time 7093.9655 according to lazer,
which was also a hyperfruit.

The broken replay on this map included one frame at time 7093, with the
catcher position before the hyperdash, and one frame at time 7097,
with the catcher position *after* the hyperdash. Which meant that
the replay handler moved *out of the way* of the hyperfruit at time
7093.9655, deciding that it is *after* the replay frame that was
supposed to be catching it.

(For reference, the relevant replay playback code is here:

    3da5831075/osu.Game.Rulesets.Catch/Replays/CatchFramedReplayInputHandler.cs (L20-L31)

Note the handling of `position`. Any frame with an action is important,
which means that as long as any key is held, interpolation will not
take place.)

On stable this is not a thing, because the fruit's end time was being
truncated to `int`, therefore moving it back to time 7093 and restoring
temporal integrity.

This probably doesn't matter in other rulesets that much because
the input tolerances in something like osu! or taiko are much higher.
catch is rather knife-edge, what with mappers doing the "edge dash" /
"pixel jump" stuff (tl;dr: placing a circle just barely outside of
hyperdash range, so that a perfect normal dash is required to catch it).
Thus, this is applied locally to catch for now until proven necessary
to put it elsewhere too.

osu.Game.Rulesets.Catch/Objects/JuiceStream.cs

@@ -118,7 +118,7 @@ namespace osu.Game.Rulesets.Catch.Objects
                         AddNested(new Droplet
                         {
                             Samples = dropletSamples,
-                            StartTime = e.Time,
+                            StartTime = (int)e.Time,
                             X = EffectiveX + Path.PositionAt(e.PathProgress).X,
                         });
                         break;
@@ -129,7 +129,7 @@ namespace osu.Game.Rulesets.Catch.Objects
                         AddNested(new Fruit
                         {
                             Samples = this.GetNodeSamples(nodeIndex++),
-                            StartTime = e.Time,
+                            StartTime = (int)e.Time,
                             X = EffectiveX + Path.PositionAt(e.PathProgress).X,
                         });
                         break;