Fix v1 summary/total with ES/OS storage backend

``metric_types`` is used as a list in ``_build_must``, so we need to
pass ``service`` as a single-itemed list.

Story: 2011128
Task: 50106
Change-Id: I144a005c180ed67a16985f93efa930ddf937c989

cloudkitty/storage/v2/elasticsearch/client.py

@@ -366,6 +366,8 @@ class ElasticsearchClient(object):
         if not paginate:
             offset = 0
 
+        metric_types = [metric_types] if metric_types else None
+
         must = self._build_must(begin, end, metric_types, filters)
         should = self._build_should(filters)
         composite = self._build_composite(groupby) if groupby else None

cloudkitty/storage/v2/opensearch/client.py

@@ -363,6 +363,8 @@ class OpenSearchClient(object):
         if not paginate:
             offset = 0
 
+        metric_types = [metric_types] if metric_types else None
+
         must = self._build_must(begin, end, metric_types, filters)
         should = self._build_should(filters)
         composite = self._build_composite(groupby) if groupby else None

releasenotes/notes/fix-v1-summary-and-total-with-es-os-backend-9540741b80819672.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixed a bug where ``openstack rating summary get -s <service>`` and
+    ``openstack rating total get -s <service>`` would fail when using the
+    Elasticsearch or OpenSearch storage backends. See story 2011128
+    <https://storyboard.openstack.org/#!/story/2011128>`_ for more details.