ui: remove invalid properties

(nm-connection-editor:13827): Gtk-WARNING **: GtkTable does not have a property called expand
(nm-connection-editor:13827): Gtk-WARNING **: GtkTable does not have a property called fill
(nm-connection-editor:13827): Gtk-WARNING **: GtkTable does not have a property called position

Grr, that's not easy to find which objects have the bad properties. It would
be nice if Gtk bothers to make better logs.