Activate neutron L2 Gateway extension

Disable l2gw agent by default to prevent unwanted connection attempts to
absent hardware switch (will be emulated/enabled by test suite on demand).

Change-Id: Iaf6da1e0f73f474d6eaee2b15e7613d58b129150
Related-Prod: PROD-18748
diff --git a/classes/cluster/virtual-offline-pike-ovs-dpdk/openstack/gateway.yml b/classes/cluster/virtual-offline-pike-ovs-dpdk/openstack/gateway.yml
index 028c83d..fb39eb4 100644
--- a/classes/cluster/virtual-offline-pike-ovs-dpdk/openstack/gateway.yml
+++ b/classes/cluster/virtual-offline-pike-ovs-dpdk/openstack/gateway.yml
@@ -11,6 +11,12 @@
     external_interface: ens6
     interface_mtu: 9000
     linux_system_codename: xenial
+  neutron:
+    gateway:
+      l2gw:
+        enabled: false
+        ovsdb_hosts:
+          ovsdbx: 127.0.0.1:6632
   linux:
     network:
       bridge: openvswitch