[ACS44] cherry pick 5e80e5d33d9a295b91cdba9377f52d9d963d802a

[Edison Su]

If Vpc public network with snat enabled, mgt server will send down "vlan-id" 
instead of "vlan://vlan-id" in ipassoccommand, which will cause issue on the 
hypervisor resource to program VR.