TestMinBwQoSOvs must call the correct methods
TestMinBwQoSOvs must call the correct methods

Minimum bandwidth rules and policies set in OVS can be found using
the methods:
  - OVSBridge._find_qos()
  - OVSBridge._find_queue(port_id)

The methods currently used are incorrect and are not testing correctly
the real status of the OVS DB.

Change-Id: Ibf2b06439a3cf6a40fec0435b4305a93a5629fd8
Closes-Bug: #1848220

openstack/neutron,openstack/neutron,mahak/neutron,mahak/neutron,mahak/neutron,openstack/neutron