refactor notification test to work with either format
refactor notification test to work with either format

The _test_notification_operation function only works with the
`basic` notification format.

For the `cadf` format to work, it is necessary to mock the
_create_cadf_payload call.

Change-Id: I982fcead0f6cb89a13057ee5275087d2e32612cc
Related-Bug: #1641660

rajalokan/keystone,mahak/keystone,openstack/keystone,ilay09/keystone,ilay09/keystone,openstack/keystone,rajalokan/keystone,mahak/keystone,mahak/keystone,rajalokan/keystone,ilay09/keystone,openstack/keystone