QmlDesigner: Fix Connections in ConnectionsEditor

Fix Implicitly defined onFoo properties in Connections are deprecated.

Change-Id: I0f2460dd4b69c070f4982ca0ec13b19cfda0342b
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Qt CI Patch Build Bot <ci_patchbuild_bot@qt.io>

share/qtcreator/qmldesigner/connectionseditor/ConnectionsDialog.qml

@@ -36,7 +36,6 @@ PopupDialog {
             property int currentTypeIndex: backend.signal.id.currentIndex ?? 0
             onCurrentTypeIndexChanged: target.currentIndex = target.currentTypeIndex
         }
-
     }
 
     ConnectionsDialogForm {
@@ -44,10 +43,9 @@ PopupDialog {
 
         Connections {
             target: root.backend
-              onPopupTargetRemoved: {
+            function onPopupTargetRemoved() {
                 root.close()
             }
         }
     }
-
 }