Revert incorrect end position optimisation

Closes https://github.com/ppy/osu/issues/26867.

Reverts 882f490390
and ce643aa68f.

The applied optimisation may have been valid as long as it was
constrained to `Slider`. But it is not, as `SliderTailCircle` stores a
local copy of the object position. And as the commit message of
ce643aa68f states, this could be bypassed
by some pretty hacky delegation from `SliderTailCircle.Position` to the
slider, but it'd also be pretty hacky because it would make flows like
`PositionBindable` break down.

Long-term solution is to probably remove bindables from hitobjects.

osu.Game.Rulesets.Osu/Objects/Slider.cs

@@ -98,7 +98,7 @@ public int RepeatCount
             set
             {
                 repeatCount = value;
-                endPositionCache.Invalidate();
+                updateNestedPositions();
             }
         }
 
@@ -165,7 +165,7 @@ public double SliderVelocityMultiplier
         public Slider()
         {
             SamplesBindable.CollectionChanged += (_, _) => UpdateNestedSamples();
-            Path.Version.ValueChanged += _ => endPositionCache.Invalidate();
+            Path.Version.ValueChanged += _ => updateNestedPositions();
         }
 
         protected override void ApplyDefaultsToSelf(ControlPointInfo controlPointInfo, IBeatmapDifficultyInfo difficulty)