autotest-firewalld-add-service: Supress pylint error on py 2.4

The only way we can catch py 2.4 non compliances is by
running pylint on the entire tree on py 2.4 systems. So,
even though this script would never be used on such
systems, we need them checked, so supress the pylint
error here.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>