Updated grafana dashboard with dynamic rate_interval

- added in one place the rate_interval variable instead of static "[1m]".

Related-Bug: PROD-30388

Change-Id: I0ec065d5094aa34dff7c1077dd7dd372a2965592
diff --git a/nova/files/grafana_dashboards/hypervisor_prometheus.json b/nova/files/grafana_dashboards/hypervisor_prometheus.json
index 7465b00..52fb58e 100644
--- a/nova/files/grafana_dashboards/hypervisor_prometheus.json
+++ b/nova/files/grafana_dashboards/hypervisor_prometheus.json
@@ -798,7 +798,7 @@
           "steppedLine": false,
           "targets": [
             {
-              "expr": "irate(libvirt_domain_info_cpu_time_seconds_total{host=\"$host\",domain=\"$instance\"}[1m])",
+              "expr": "irate(libvirt_domain_info_cpu_time_seconds_total{host=\"$host\",domain=\"$instance\"}[$rate_interval])",
               "format": "time_series",
               "intervalFactor": 2,
               "legendFormat": "",
@@ -952,7 +952,7 @@
           "steppedLine": false,
           "targets": [
             {
-              "expr": "irate(libvirt_domain_block_stats_read_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$disk\"}[1m])",
+              "expr": "irate(libvirt_domain_block_stats_read_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$disk\"}[$rate_interval])",
               "format": "time_series",
               "intervalFactor": 2,
               "legendFormat": "read",
@@ -961,7 +961,7 @@
               "step": 10
             },
             {
-              "expr": "irate(libvirt_domain_block_stats_write_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$disk\"}[1m])",
+              "expr": "irate(libvirt_domain_block_stats_write_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$disk\"}[$rate_interval])",
               "format": "time_series",
               "intervalFactor": 2,
               "legendFormat": "write",
@@ -1038,7 +1038,7 @@
           "steppedLine": false,
           "targets": [
             {
-              "expr": "irate(libvirt_domain_interface_stats_receive_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$interface\"}[1m])",
+              "expr": "irate(libvirt_domain_interface_stats_receive_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$interface\"}[$rate_interval])",
               "format": "time_series",
               "intervalFactor": 2,
               "legendFormat": "rx",
@@ -1047,7 +1047,7 @@
               "step": 20
             },
             {
-              "expr": "irate(libvirt_domain_interface_stats_transmit_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$interface\"}[1m])",
+              "expr": "irate(libvirt_domain_interface_stats_transmit_bytes_total{host=\"$host\",domain=\"$instance\",target_device=\"$interface\"}[$rate_interval])",
               "format": "time_series",
               "intervalFactor": 2,
               "legendFormat": "tx",
@@ -1215,7 +1215,49 @@
         "tagsQuery": "",
         "type": "query",
         "useTags": false
-     }
+      },
+      {
+        "allValue": null,
+        "current": {
+          "text": "3m",
+          "value": "3m"
+        },
+        "hide": 0,
+        "includeAll": false,
+        "label": null,
+        "multi": false,
+        "name": "rate_interval",
+        "options": [
+          {
+            "selected": false,
+            "text": "1m",
+            "value": "1m"
+          },
+          {
+            "selected": true,
+            "text": "3m",
+            "value": "3m"
+          },
+          {
+            "selected": false,
+            "text": "5m",
+            "value": "5m"
+          },
+          {
+            "selected": false,
+            "text": "10m",
+            "value": "10m"
+          },
+          {
+            "selected": false,
+            "text": "15m",
+            "value": "15m"
+          }
+        ],
+        "query": "1m,3m,5m,10m,15m",
+        "skipUrlSync": false,
+        "type": "custom"
+      }
     ]
   },
   "time": {