Use gnocchi search api to check gnocchi resources

When running the tests against production cloud, the resource list call
would return tons of records, so it's better to use resource search api
instead to check the resources.

Change-Id: I723f99e5b19ddf4dc2d9c20738e818b7399f54a4

telemetry_tempest_plugin/scenario/telemetry_integration_gabbits/autoscaling.yaml

@@ -54,14 +54,18 @@ tests:
 
     - name: check gnocchi resources
       desc: Check the gnocchi resources for this two servers exists
-      url: $ENVIRON['GNOCCHI_SERVICE_URL']/v1/resource/instance
-      method: GET
+      url: $ENVIRON['GNOCCHI_SERVICE_URL']/v1/search/resource/instance
+      method: POST
+      request_headers:
+          content-type: application/json
+      data:
+          =:
+              server_group: $RESPONSE['$.servers[0].metadata."metering.server_group"']
       poll:
           count: 30
           delay: 1
-      response_strings:
-          - '"id": "$RESPONSE["$.servers[0].id"]"'
-          - '"id": "$RESPONSE["$.servers[1].id"]"'
+      response_json_paths:
+          $.`len`: 2
 
     - name: check event
       desc: Check panko for new instance.create.end event