a0456d9990
In order for network availability zone field to have the right value in the |TVD plugin, we need to separate the az-hints code from the az code. the az hints is the same for v&v3 plugins and updated using a registered extend method. the az field logic is different in each plugin and updated direction by get_network_availability_zones Change-Id: Ife423b92d8861d8cde9a7ae265f86382505d2541