Revert "Fix config group for SSL in tempest test"

It was a good attempt to update Tempest plugin, but Tempest folks reverted a patch in Tempest:
https://review.openstack.org/#/c/357907/

So now Aodh's gate is broken because the parameters are not in the right section. Let's revert it until things are cleaned up in Tempest and Oslo.config.

This reverts commit 3d3ad69e367456520666d8ca32e67a5ed03d24a4.

Change-Id: I5e724d870e029b9b72484b14c89f9d65de4615e9

aodh/tests/tempest/service/client.py

@@ -106,8 +106,8 @@ class Manager(manager.Manager):
 
     default_params = {
         'disable_ssl_certificate_validation':
-            CONF.service_clients.disable_ssl_certificate_validation,
-        'ca_certs': CONF.service_clients.ca_certificates_file,
+            CONF.identity.disable_ssl_certificate_validation,
+        'ca_certs': CONF.identity.ca_certificates_file,
         'trace_requests': CONF.debug.trace_requests
     }