test: Skip `test_use_global_dns_even_for_with_static_ip` in k8s CI

In K8S, nmstate is running in a container without access to
`/etc/NetworkManager` folder of host. Hence we should skip the
`test_use_global_dns_even_for_with_static_ip` test case.

Signed-off-by: Gris Ge <fge@redhat.com>