Remove unnecessary anchor

Fixes review comment https://github.com/Ultimaker/Cura/pull/10491#discussion_r713124155.

CURA-8421

resources/qml/ApplicationSwitcher/ApplicationSwitcher.qml

@@ -22,8 +22,6 @@ Item
 
         background: Item
         {
-            anchors.fill: parent
-
             Rectangle
             {
                 anchors.fill: parent