Ticket 48953 - Skip labelling and unlabelling ports during the test
    
    Description:
        In CI creating and removing instances takes most of the
        time, because of labelling/unlabelling ports via semanage.
    
    Fix description:
        Skip labelling and unlabelling if special environment
        variables are present: DS_SKIP_LABEL and DS_SKIP_UNLABEL
        respectively.
    
    https://fedorahosted.org/389/ticket/48953
    
    Reviewed by: nhosoi@redhat.com (Thanks!)