Don't show context menu button if it is empty

It will likely be empty for guest accounts on networks where the administrator is the only one with rights to access other people's prints.

Contributes to issue CURA-9220.

plugins/UM3NetworkPrinting/resources/qml/MonitorPrintJobCard.qml

@@ -206,7 +206,11 @@ Item
         onClicked: enabled ? contextMenu.switchPopupState() : {}
         visible:
         {
-            if (!printJob)
+            if(!printJob)
+            {
+                return false;
+            }
+            if(!contextMenu.hasItems)
             {
                 return false;
             }