Upgrade: Fix upgrade of NIS Server configuration
    
    Former upgrade file always created the NIS Server container, that caused
    the ipa-nis-manage did not set all required NIS maps. Default creation
    of container has been removed.
    
    Updating of NIS Server configuration and
    NIS maps is done only if the NIS Server container exists.
    
    https://fedorahosted.org/freeipa/ticket/5507
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>