.Values.network.auto_bridge_add is a global config. So in multi nodes
deployment, it requires that all hosts have the same nic names. This is
a strict limit.
This patch is to support per-host auto_bridge_add, so that we can define
different auto_bridge_add for hosts.
Also, this patch move .network.auto_bridge_add to .conf.auto_bridge_add
Change-Id: I4a4d6efbbfe073d035bc5c03700fbe998e708d0f
Story: 2005059
Task: 29601
6e2e4aba8d