status/volume: Clear device menus when unsetting stream

Otherwise we end up accumulating devices when pipewire crashes or
is restarted.

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6142

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2558>

js/ui/status/volume.js

@@ -83,6 +83,8 @@ const StreamSlider = GObject.registerClass({
             this._connectStream(this._stream);
             this._updateVolume();
         } else {
+            this._deviceSection.removeAll();
+            this._deviceItems.clear();
             this.emit('stream-updated');
         }