Remove conditional inhibiting seek when beatmap change is not allowed

In testing I can't find a reason for this to exist. Blaming back shows
that it existed before we had `AllowTrackControl` and was likely being
used as a stop-gap measure to achieve the same thing. It's existed since
over 6 years ago.

Let's give removing it a try to fix some usability concerns?

Closes https://github.com/ppy/osu/issues/29563.

osu.Game/Overlays/MusicController.cs

@@ -115,7 +115,7 @@ namespace osu.Game.Overlays
             seekDelegate?.Cancel();
             seekDelegate = Schedule(() =>
             {
-                if (beatmap.Disabled || !AllowTrackControl.Value)
+                if (!AllowTrackControl.Value)
                     return;
 
                 CurrentTrack.Seek(position);