Remove unnecessary sample stop in Restart()

It is unnecessary, as a successful restart will exit the current player
screen, and `OnExiting()` has another `StopSampleAndRemoveFilters()`
call, which means that in the restart flow the sample was actually
getting stopped twice.

Standard exit flow is fine, it only stopped the sample once.

osu.Game/Screens/Play/Player.cs

@@ -678,7 +678,6 @@ namespace osu.Game.Screens.Play
 
             sampleRestart?.Play();
             RestartRequested?.Invoke(quickRestart);
-            failAnimationLayer.StopSample();
 
             PerformExit(false);
         }