To have connectivity through public network to the vms which are on
various nodes in the ci job, we need to configure special bridge called
"br-infra" and connect this bridge with br-ex with patch ports.
This can be done using "multi-node-bridge" role from zuul roles and
"multi-node-setup" added to this repository.
Change-Id: I80d7d2bed8291ba21ddc68b48fef5d0aac996b39
d833b3d2ee