bump the server_cockpit_autoupdate timeout to help F30/F31
    
    We seem to be seeing the bug this works around:
    https://bugzilla.redhat.com/show_bug.cgi?id=1765685
    in F30 and F31 update tests even with this wait. At least, it
    looks that way. Trying this to see if a longer wait helps.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>