Replace uuid.uuid4() with uuidutils.generate_uuid()
Replace uuid.uuid4() with uuidutils.generate_uuid()

Since oslo.utils provide the ability to generate the uuid string,
and some others use oslo.utils[0] too. For consistency, this ps
replaces uuid.uuid4() with uuidutils.generate_uuid().

Change-Id: I9adc4f478d3107c27578941f45896649cc82630f

openstack/networking-cisco,noironetworks/networking-cisco,openstack/networking-cisco,noironetworks/networking-cisco