[OVN] Configure public bridge enabled by default

This patch makes the OVN_L3_CREATE_PUBLIC_NETWORK configuration True by
default. This option makes the OVN lib in DevStack create & configure
the external bridge, matching the same behavior from the OVS driver
in DevStack.

Change-Id: Icda53b95fdc3c169ac48a6ec4343c87ba404baa4
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>

Author: umago

.zuul.yaml

@@ -468,7 +468,6 @@
         SWIFT_HASH: 1234123412341234
         DEBUG_LIBVIRT_COREDUMPS: true
         NOVA_VNC_ENABLED: true
-        OVN_L3_CREATE_PUBLIC_NETWORK: true
         OVN_DBS_LOG_LEVEL: dbg
       devstack_local_conf:
         post-config:

lib/neutron_plugins/ovn_agent

@@ -95,6 +95,7 @@ OVN_META_DATA_HOST=${OVN_META_DATA_HOST:-$(ipv6_unquote $SERVICE_HOST)}
 
 # If True (default) the node will be considered a gateway node.
 ENABLE_CHASSIS_AS_GW=$(trueorfalse True ENABLE_CHASSIS_AS_GW)
+OVN_L3_CREATE_PUBLIC_NETWORK=$(trueorfalse True OVN_L3_CREATE_PUBLIC_NETWORK)
 
 export OVSDB_SERVER_LOCAL_HOST=$SERVICE_LOCAL_HOST
 if [[ "$SERVICE_IP_VERSION" == 6 ]]; then