Remove reference to nonexistent property source size in UM.ColorImage which was causing add printer page to be empty

CURA-9098

resources/qml/WelcomePages/AddNetworkPrinterScrollView.qml

@@ -208,7 +208,6 @@ Item
                 anchors.verticalCenter: parent.verticalCenter
                 height: troubleshootingLabel.height
                 width: height
-                sourceSize.height: width
                 color: UM.Theme.getColor("text_link")
                 source: UM.Theme.getIcon("LinkExternal")
             }