fix metrics

Signed-off-by: husharp <jinhao.hu@pingcap.com>

Author: HuSharp

metrics/grafana/pd.json

@@ -1670,7 +1670,8 @@
           "tableColumn": "idalloc",
           "targets": [
             {
-              "expr": "pd_cluster_id{k8s_cluster=\"$k8s_cluster\", tidb_cluster=\"$tidb_cluster\", instance=\"$instance\", type=\"idalloc\"}","format": "time_series",
+              "expr": "pd_cluster_id{k8s_cluster=\"$k8s_cluster\", tidb_cluster=\"$tidb_cluster\", instance=\"$instance\", type=\"idalloc\"}",
+              "format": "time_series",
               "hide": false,
               "instant": true,
               "intervalFactor": 2,