Set several extra schema keys for update notification test
    
    GNOME got even more clever-clever about only checking for and
    notifying about updates after a certain amount of time, so we
    need to fake it out even harder. See
    https://bugzilla.redhat.com/show_bug.cgi?id=1930401 and
    https://wiki.gnome.org/Design/Apps/Software/Updates#Tentative_Design
    Note the test will still fail for now as there is an actual bug
    that needs fixing, but once the fix is in, this should work.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>