[bgpvpn] Use Linux bridge for odl01 public network

Previously, we used a single interface definition for public network
on odl01 node, which does not work well for baremetal setups that
use a tagged VLAN public network, like ericsson-pod1.

Change-Id: I10ff7c105406691011e94e06b2f099dc2cdf8a06
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
(cherry picked from commit b8a85f1c6213e3abaf295e7662c4b0df4570039b)