Fix tests failing due to base logic firing

It turns out that the changelog code was semi-intentionally relying on
the request to get release streams to be slow to initially show the
listing of all streams.

Locally suppress the base tab control logic to fix this.

osu.Game/Overlays/Changelog/ChangelogUpdateStreamControl.cs

@@ -8,5 +8,11 @@ namespace osu.Game.Overlays.Changelog
     public class ChangelogUpdateStreamControl : OverlayStreamControl<APIUpdateStream>
     {
         protected override OverlayStreamItem<APIUpdateStream> CreateStreamItem(APIUpdateStream value) => new ChangelogUpdateStreamItem(value);
+
+        protected override void LoadComplete()
+        {
+            // suppress base logic of immediately selecting first item if one exists
+            // (we always want to start with no stream selected).
+        }
     }
 }