Give snapping toolbox enough hover delay for interaction with expand button

With 0 delay, if the `SettingsToolboxGroup` has been contracted via
button, there's no chance to be able to expand it via button again.

This is temporary at best just to keep things working somewhat, not sure
if the expansion logic will still be required in editor redesign, so
deciding to roll with it for now.

osu.Game.Rulesets.Osu/Edit/OsuToolboxComposite.cs

@@ -106,6 +106,8 @@ protected override bool OnScroll(ScrollEvent e)
 
         private class ExpandingToolboxContainer : ExpandingContainer
         {
+            protected override double HoverExpansionDelay => 250;
+
             public ExpandingToolboxContainer()
                 : base(130, 250)
             {