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.

(cherry picked from commit a4226c4598efe7284c663e0f5ed1803162f3251e)