Streaming: support streaming and a javascript test datasource (#16729)

pkg/tsdb/testdata/scenarios.go

@@ -225,6 +225,15 @@ func init() {
 		},
 	})
 
+	registerScenario(&Scenario{
+		Id:   "streaming_client",
+		Name: "Streaming Client",
+		Handler: func(query *tsdb.Query, context *tsdb.TsdbQuery) *tsdb.QueryResult {
+			// Real work is in javascript client
+			return tsdb.NewQueryResult()
+		},
+	})
+
 	registerScenario(&Scenario{
 		Id:   "table_static",
 		Name: "Table Static",