Updates downsample test

Author: picandocodigo

tests/indices/downsample.yml

@@ -17,6 +17,34 @@ setup:
               time_series:
                 start_time: "2021-04-28T00:00:00Z"
                 end_time: "2021-04-29T00:00:00Z"
+          mappings:
+            properties:
+              "@timestamp":
+                type: date
+              metricset:
+                type: keyword
+                time_series_dimension: true
+              k8s:
+                properties:
+                  pod:
+                    properties:
+                      uid:
+                        type: keyword
+                        time_series_dimension: true
+                      network:
+                        properties:
+                          tx:
+                            type: long
+                            time_series_metric: gauge
+                          rx:
+                            type: long
+                            time_series_metric: gauge
+                          sent:
+                            type: long
+                            time_series_metric: counter
+                          received:
+                            type: long
+                            time_series_metric: counter
 
   # Make the downsample downsample_index index read-only
   - do: