In Netvirt 3 node cluster default ports and manager are not deleted in operational data store

In Netvirt 3 node cluster, added bridge "br-s1" manually, it got created and deleted successfully and the data are getting deleted in both OVS and operational side. But the default bridge br-int, br-ex and manager are not deleted in operational side but it got deleted in OVS side. Also tested manually and observed the same behaviour.

Refernce:
https://logs.opendaylight.org/sandbox/jenkins091/netvirt-csit-3node-openstack-mitaka-openstack-beryllium/6/archives/log.html.gz

Reproduce this issue, following below steps
1) 3-node cluster and stack is up
2) Delete Internal bridge "sudo ovs-vsctl del-br br-int" in OVS
3) Delete External bridge "sudo ovs-vsctl del-br br-ex" in OVS
4) Delete the manager "sudo ovs-vsctl del-manager" in OVS
5) Verify the operational data store