tempest: remove ceilometer-api alarm

This is to keep in sync with Id89130fd8a782dea863c85b37a919fbf0f0897dd

Change-Id: I7f441988c6f908261ff5de81b7e0ea59a6a0b9fa
diff --git a/telemetry_tempest_plugin/aodh/api/base.py b/telemetry_tempest_plugin/aodh/api/base.py
index 92339b7..1035df7 100644
--- a/telemetry_tempest_plugin/aodh/api/base.py
+++ b/telemetry_tempest_plugin/aodh/api/base.py
@@ -46,7 +46,7 @@
     def create_alarm(cls, **kwargs):
         body = cls.alarming_client.create_alarm(
             name=data_utils.rand_name('telemetry_alarm'),
-            type='threshold', **kwargs)
+            type='gnocchi_aggregation_by_metrics_threshold', **kwargs)
         cls.alarm_ids.append(body['alarm_id'])
         return body