Option `service_provider` is defined in neutron_lbaas.conf, there
is a duplicated config option in neutron.conf, it should be removed
there. Otherwise neutron-server will not be able to start with error:
'Invalid: Driver
neutron_lbaas.drivers.haproxy.plugin_driver.HaproxyOnHostPluginDriver is
not unique across providers'
Change-Id: I3fc379535eb00bbcb23aa41de95ca8161883a181
Closes-bug: #1625174