Disable updates harder in Workstation and Robotics (#2064077)

Just setting `download-updates=false` seems not to be enough any
more, we get update notifications in live images currently. This
should fix that and also disable the Updates pane on GNOME
Software in the live environment, which is a nice improvement.

https://gitlab.gnome.org/GNOME/gnome-software/-/issues/1683#note_1408750

Signed-off-by: Adam Williamson <awilliam@redhat.com>

fedora-live-robotics.ks

@@ -107,6 +107,7 @@ FOE
 # disable updates plugin
 cat >> /usr/share/glib-2.0/schemas/org.gnome.software.gschema.override << FOE
 [org.gnome.software]
+allow-updates=false
 download-updates=false
 FOE
 

fedora-live-workstation.ks

@@ -20,6 +20,7 @@ cat >> /etc/rc.d/init.d/livesys << EOF
 # disable gnome-software automatically downloading updates
 cat >> /usr/share/glib-2.0/schemas/org.gnome.software.gschema.override << FOE
 [org.gnome.software]
+allow-updates=false
 download-updates=false
 FOE