Load neutron_fwaas.conf with '--config-file' for neutron-server
Load neutron_fwaas.conf with '--config-file' for neutron-server

This commit enables to load neutron_fwaas.conf for neutron-server
correctly and 'FIREWALL_V2' will be registered into service_provider.

Closes-Bug: #1786413
Co-Authored-By: Cao Xuan Hoang <ff2052e2b68b6e1a8b769cfddb4e24a60a87e163@vn.fujitsu.com>
Change-Id: I9401a797f1aff1b7c603b8795f9c603289e4589e

openstack/neutron-fwaas,openstack/neutron-fwaas