Add Metrics Command Capability check to test that needs it (elastic#133714)

I missed one in elastic#133495

This test also uses the TS command and requires the metrics_command capability check.

Author: not-napoleon

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/esql/46_downsample.yml

@@ -260,7 +260,7 @@ setup:
         - method: POST
           path: /_query
           parameters: []
-          capabilities: [aggregate_metric_double_implicit_casting_in_aggs]
+          capabilities: [metrics_capability, aggregate_metric_double_implicit_casting_in_aggs]
       reason: "Support for casting aggregate metric double implicitly when present in aggregations"
 
   - do: