Fix Keystone CADF notifications

* use template for transport_url that is working for kolla-kubernetes
* use transport_url parameter in DEFAULT section

Co-authored-by: Christian Berendt <berendt@betacloud-solutions.de>

Change-Id: I800b5bc4c178b5df4f208ee50944e2806fd6a7c1
Closes-bug: #1625352