Fix `KeyCounterDisplay` potentially getting stuck invisible due to autosize masking

Closes #14793.

osu.Game/Screens/Play/KeyCounterDisplay.cs

@@ -33,8 +33,6 @@ public class KeyCounterDisplay : Container<KeyCounter>
 
         public KeyCounterDisplay()
         {
-            AutoSizeAxes = Axes.Both;
-
             InternalChild = KeyFlow = new FillFlowContainer<KeyCounter>
             {
                 Direction = FillDirection.Horizontal,
@@ -42,6 +40,15 @@ public KeyCounterDisplay()
             };
         }
 
+        protected override void Update()
+        {
+            base.Update();
+
+            // Don't use autosize as it will shrink to zero when KeyFlow is hidden.
+            // In turn this can cause the display to be masked off screen and never become visible again.
+            Size = KeyFlow.Size;
+        }
+
         public override void Add(KeyCounter key)
         {
             if (key == null) throw new ArgumentNullException(nameof(key));