Start time synchronization notification helper from XDG autostart.

First, it's much simpler and robust than running it from the time sync'
NetworkManager hook.

Second, it fixes seemingly random race conditions, when the notification would
be hidden by the GNOME desktop if shown before it.

config/chroot_local-includes/etc/NetworkManager/dispatcher.d/20-time.sh

@@ -210,17 +210,9 @@ is_clock_way_off() {
 	return 1
 }
 
-start_notification_helper() {
-	export DISPLAY=':0.0'
-	export XAUTHORITY="$(echo /var/run/gdm3/auth-for-$LIVE_USERNAME-*/database)"
-	exec /bin/su -c /usr/local/bin/tails-htp-notify-user "$LIVE_USERNAME" &
-}
-
 
 ### Main
 
-start_notification_helper
-
 # Delegate time setting to other daemons if Tor connections work
 if tor_is_working; then
 	log "Tor has already opened a circuit"

config/chroot_local-includes/etc/xdg/autostart/time-sync-notify.desktop

+[Desktop Entry]
+Name=tails-htp-notify-user
+GenericName=notify user of time synchronization process
+Comment=notify user of time synchronization process
+Exec=/usr/local/bin/tails-htp-notify-user
+Terminal=false
+Type=Application
+Categories=GNOME;X-GNOME-PersonalSettings;
+NoDisplay=true
+MimeType=application/x-tails-htp-notify-user;