Enable firewall in the tests for PR CI
    
    The firewall has not been enabled in the tests for PR CI so far. With these
    steps this is done now:
    
    install_packages: Install firewalld, enable and start firewalld service.
    
    install_server: Enable firewalld services freeipa-ldap freeipa-ldaps and
    dns after server installation.
    
    run_tests: Disable firewalld services freeipa-ldap freeipa-ldaps and dns
    after server uninstallation.
    
    Related-to: https://pagure.io/freeipa/issue/7755
    Signed-off-by: Thomas Woerner <twoerner@redhat.com>
    Reviewed-By: Christian Heimes <cheimes@redhat.com>