Progress bar never indeterminate if invisible

Because if the progress bar is indeterminate, it triggers redraws for every frame to create the animation of the progress bar bouncing, regardless of whether it is visible or not. So now we make it indeterminate regardless of what state it is in.

Contributes to issue CURA-2497.

resources/qml/MonitorButton.qml

@@ -161,6 +161,10 @@ Rectangle
         visible: showProgress;
         indeterminate:
         {
+            if(!showProgress)
+            {
+                return false; //Never be indeterminate when not visible, since that triggers a redraw of the screen.
+            }
             switch(Cura.MachineManager.printerOutputDevices[0].jobState)
             {
                 case "pausing":