[TD] vertex dialog: fix vertical size
[TD] vertex dialog: fix vertical size

there was too much vertical whitespace below the actual dialog
-> remove superfluous spacer and correct size policy

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master