Remove schedule in panel load

It was causing selection/deselection of all mods to work improperly if a
select/deselect all operation was requested before the panel was
scrolled into view.

In general the schedule was an over-optimisation - the game-global set
of available mods shouldn't be changing so often as to warrant such an
aggressive debounce.

osu.Game/Overlays/Mods/ModColumn.cs

@@ -275,7 +275,7 @@ namespace osu.Game.Overlays.Mods
                 return;
 
             localAvailableMods = newMods;
-            Scheduler.AddOnce(loadPanels);
+            loadPanels();
         }
 
         private CancellationTokenSource? cancellationTokenSource;