Remove [octavia]/base_url option from neutron.conf

This configuration option was only used by neutron-lbaas, which is now
retired. It should have been added to neutron_lbaas.conf.j2 instead.

Change-Id: Iba591473abf4304413eca0d84e0b2be197c527fc

ansible/roles/neutron/templates/neutron.conf.j2

@@ -152,11 +152,6 @@ drivers = ovs
 drivers = ovs
 {% endif %}
 
-{% if enable_octavia | bool %}
-[octavia]
-base_url = {{ octavia_internal_endpoint }}
-{% endif %}
-
 {% if enable_designate | bool %}
 [designate]
 url = {{ designate_internal_endpoint }}/v2