When QoS is set in the neutron-api charm, the neutron-openvswitch
charm needs to add 'extensions = qos' to the sriov_agent.ini
file.
Closes-bug: #1938277
Change-Id: I44fbf5991d2606161b1bcbc064d4bc68a2fbbb5b
(cherry picked from commit 2a6cba8e6f)
(cherry picked from commit 561a44e948)
(cherry picked from commit 4a8f542f78)
(cherry picked from commit 246128d98e)