senlin: add missing cafile parameter

The cafile parameter in the authentication section is required
in the senlin.conf configuration file when working with
self-signed certificates.

Change-Id: I3cd43cc7f43782a6c1d701a3e5b977bbc42e3719

ansible/roles/senlin/templates/senlin.conf.j2

@@ -14,6 +14,7 @@ workers = {{ senlin_api_workers }}
 
 [authentication]
 auth_url = {{ keystone_internal_url }}
+cafile = {{ openstack_cacert }}
 service_username = {{ senlin_keystone_user }}
 service_password = {{ senlin_keystone_password }}
 service_project_name = service

releasenotes/notes/senlin-authentication-cafile-4fe5e2f79769c872.yaml

+---
+features:
+  - |
+    In the configuration template of the Senlin service the ``cafile``
+    parameter is now set by default in the ``authentication`` section.
+    This way the use of self-signed certificates on the internal Keystone
+    endpoint is also usable in the Senlin service.