Fix Request_Handler_Avg_Idle_Percent metric bug (#12289)

Signed-off-by: OwenCorrigan76 <owencorrigan76@gmail.com>

Author: OwenCorrigan76

packaging/examples/metrics/strimzi-metrics-reporter/grafana-dashboards/strimzi-kafka.json

@@ -2312,7 +2312,7 @@
       "targets": [
         {
           "datasource": "${DS_PROMETHEUS}",
-          "expr": "sum(kafka_server_kafkarequesthandlerpool_requesthandleravgidlepercent_total{namespace=\"$kubernetes_namespace\",strimzi_io_cluster=\"$strimzi_cluster_name\",kubernetes_pod_name=~\"$strimzi_cluster_name-$kafka_broker\"}*100) by (kubernetes_pod_name)",
+          "expr": "sum(irate(kafka_server_kafkarequesthandlerpool_requesthandleravgidlepercent_total{namespace=\"$kubernetes_namespace\",strimzi_io_cluster=\"$strimzi_cluster_name\",kubernetes_pod_name=~\"$strimzi_cluster_name-$kafka_broker\"}[$__rate_interval]) / 1e9 * 100) by (kubernetes_pod_name)",
           "format": "time_series",
           "hide": false,
           "intervalFactor": 1,