feat(dataproxy): set flush interval, need a setting for this

pkg/api/dataproxy.go

@@ -61,7 +61,7 @@ func NewReverseProxy(ds *m.DataSource, proxyPath string, targetUrl *url.URL) *ht
 		req.Header.Del("Set-Cookie")
 	}
 
-	return &httputil.ReverseProxy{Director: director}
+	return &httputil.ReverseProxy{Director: director, FlushInterval: time.Millisecond * 200}
 }
 
 func getDatasource(id int64, orgId int64) (*m.DataSource, error) {