This patch adds new config option NEUTRON_ENFORCE_NEW_DEFAULTS which
if set to True will deploy Neutron with enforce new rbac defaults and
scopes.
It will also use SYSTEM_ADMIN user to interact with Neutron where it is
needed.
Depends-On: https://review.opendev.org/c/openstack/neutron/+/798821
Change-Id: I14d934f0deced34d74003b92824cad3c44ec4f5e