Fix wrong configuration for `service_plugins`
Fix wrong configuration for `service_plugins`

Change `service_plugins =
neutron.plugins.services.agent_loadbalancer.plugin.LoadBalancerPlugin`
to
`service_plugins =
neutron.services.loadbalancer.plugin.LoadBalancerPlugin`

Fixes bug #1257210

Change-Id: Ida84acc3ba3d167a3a39c38f55b0c9de781f1b56

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,openstack/openstack-manuals,saeki-masaki/openstack-manuals,Akasurde/openstack-manuals,gongysh2004/openstack-manual,Akasurde/openstack-manuals,kairoaraujo/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,gongysh2004/openstack-manual,kairoaraujo/openstack-manuals,potsmaster/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals