[th/ovs-external-ids-rh1866227] add @ovs_external_ids test

test for OVS external IDs.

See

• https://bugzilla.redhat.com/show_bug.cgi?id=1866227
• NetworkManager!679 (closed)

A successful run is here: https://desktopqe-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/beaker-NetworkManager-gitlab-trigger-code-upstream/1928/artifact/artifacts/

@Build:master