Merge pull request ppy#6180 from EVAST9919/grid-alloc

Invalidate `GridContainer` only on DrawSize change

osu.Framework/Graphics/Containers/GridContainer.cs

@@ -139,7 +139,7 @@ protected override void Update()
         }
 
         private readonly Cached cellContent = new Cached();
-        private readonly LayoutValue cellLayout = new LayoutValue(Invalidation.DrawInfo | Invalidation.RequiredParentSizeToFit);
+        private readonly LayoutValue cellLayout = new LayoutValue(Invalidation.DrawSize);
         private readonly LayoutValue cellChildLayout = new LayoutValue(Invalidation.RequiredParentSizeToFit | Invalidation.Presence, InvalidationSource.Child);
 
         private CellContainer[,] cells = new CellContainer[0, 0];