Adjust Prometheus Stats dashboard

"handler" label value was changed in Prometheus 2.12.0, now it
contains "/api/v1/" prefix.

Change-Id: Id918827a8229574b7a56ede5c40976a14052d361
Related-PROD: PROD-32407
diff --git a/grafana/files/dashboards/prometheus/prometheus_stats_prometheus.json b/grafana/files/dashboards/prometheus/prometheus_stats_prometheus.json
index 9d8c5c0..c82e597 100644
--- a/grafana/files/dashboards/prometheus/prometheus_stats_prometheus.json
+++ b/grafana/files/dashboards/prometheus/prometheus_stats_prometheus.json
@@ -648,7 +648,7 @@
       "steppedLine": false,
       "targets": [
         {
-          "expr": "rate(prometheus_http_request_duration_seconds_count{environment=\"$environment\",handler=~\"/(query|query_range)\",instance=~\"$instance:[1-9][0-9]*\"}[$rate_interval])",
+          "expr": "rate(prometheus_http_request_duration_seconds_count{environment=\"$environment\",handler=~\".*/(query|query_range)\",instance=~\"$instance:[1-9][0-9]*\"}[$rate_interval])",
           "format": "time_series",
           "hide": false,
           "intervalFactor": 2,