Account for oslo_config deprecations in aodh.conf template

Specific changes are based on the aodh-api log noting:
 * Option "auth_plugin" from group "keystone_authtoken" is deprecated. Use
   option "auth_type" from group "keystone_authtoken".
 * Option "username" from group "keystone_authtoken" is deprecated. Use option
   "user-name" from group "keystone_authtoken".

Change-Id: I295ed77d88daa1b4844eb8efde628fecdad94c03

templates/aodh.conf.j2

@@ -23,14 +23,14 @@ connection = {{ aodh_connection_string }}
 
 [keystone_authtoken]
 insecure = {{ keystone_service_internaluri_insecure | bool }}
-auth_plugin = {{ aodh_keystone_auth_plugin }}
+auth_type = {{ aodh_keystone_auth_plugin }}
 signing_dir = {{ aodh_system_user_home }}/cache/api
 auth_url = {{ keystone_service_adminuri }}
 auth_uri = {{ keystone_service_internaluri }}
 project_domain_id = {{ aodh_service_project_domain_id }}
 user_domain_id = {{ aodh_service_user_domain_id }}
 project_name = {{ aodh_service_project_name }}
-username = {{ aodh_service_user_name }}
+user-name = {{ aodh_service_user_name }}
 password = {{ aodh_service_password }}
 
 memcached_servers = {{ memcached_servers }}