[ovn]: Enable port forwarding in neutron service plugins

This is a continuation of change id I27ac0a536624f5461809df771a58a6e57fec0661

The port_forwarding service should be included as part of the default
NeutronServicePlugins value.

Closes-Bug: #1877447
Signed-off-by: Flavio Fernandes <flaviof@redhat.com>

Change-Id: Ib35fdae76f16f7e0f993587056b7759aeceff061

deployment/neutron/neutron-base.yaml

@@ -27,7 +27,7 @@ parameters:
         from neutron.core_plugins namespace.
     type: string
   NeutronServicePlugins:
-    default: "qos,ovn-router,trunk,segments,log"
+    default: "qos,ovn-router,trunk,segments,port_forwarding,log"
     description: |
         Comma-separated list of service plugin entrypoints to be loaded from the
         neutron.service_plugins namespace.