QmlDesigner: Close the popup when model is detached

This happens when leaving the edit mode or the document
is changed.

Task-number: QDS-10707
Change-Id: I4b4e2511674d38c2d733db29070c01252c27c386
Reviewed-by: Aleksei German <aleksei.german@qt.io>

src/plugins/qmldesigner/components/connectioneditor/connectionview.cpp

@@ -169,6 +169,7 @@ void ConnectionView::modelAboutToBeDetached(Model *model)
     bindingModel()->reset();
     dynamicPropertiesModel()->reset();
     connectionModel()->resetModel();
+    connectionModel()->modelAboutToBeDetached();
 }
 
 void ConnectionView::nodeCreated(const ModelNode & /*createdNode*/)