Fix SB relay container tag checking

Author: Alex-Welsh

tools/kolla-images.py

@@ -91,6 +91,7 @@
     "neutron_eswitchd": "neutron_mlnx_agent",
     "neutron_tls_proxy": "haproxy",
     "nova_compute_ironic": "nova",
+    "ovn_sb_db_relay": "ovn",
     "redis_sentinel": "openstack",
     "swift_object_expirer": "swift",
     "tgtd": "iscsi",