Previously those functions were defined in the neutron's devstack plugin
but with [1] we moved qos related code into devstack and we missed about
moving them too.
This is follow up patch to fix that issue.
[1] https://review.opendev.org/c/openstack/devstack/+/815686
Change-Id: Icf459a2f8c6ae3c3cb29b16ba0b92766af41af30