[widgetexplorer] Don't recurse into applet's containments

The intention of this code appears to be finding system tray applets, since the systemtray is a containment within another applet/containment

However the code causes an infinit recursion since we are calling addContainment on the same containment again

The recursion also is unnecessary since corona->containments() already lists the system tray containment, so we don't need to find it by recursing through the panel's children

(cherry picked from commit c7ba560cca)

components/shellprivate/widgetexplorer/widgetexplorer.cpp

@@ -280,10 +280,6 @@ void WidgetExplorerPrivate::addContainment(Containment *containment)
 
     foreach (Applet *applet, containment->applets()) {
         if (applet->pluginMetaData().isValid()) {
-            Containment *childContainment = applet->property("containment").value<Containment *>();
-            if (childContainment) {
-                addContainment(childContainment);
-            }
             runningApplets[applet->pluginMetaData().pluginId()]++;
         } else {
             qDebug() << "Invalid plugin metadata. :(";