
This signal id comes from a signal handler on self, use the right
object when disconnecting it. Spotted by Eugene Popov at
https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2140#note_2039721.
Fixes: b3f5fdcb6
("endSessionDialog: Connect to events in the dialog itself")
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3225>