rebase this chart on cnpg provided chart

charts/postgres-cluster/prometheus_rules/cluster-long_running_transaction-warning.yaml

@@ -0,0 +1,16 @@
+{{- $alert := "CNPGClusterLongRunningTransactionWarning" -}}
+{{- if not (has $alert .excludeRules) -}}
+alert: {{ $alert }}
+annotations:
+  summary: CNPG Cluster query is taking longer than 5 minutes.
+  description: |-
+    CloudNativePG Cluster Pod {{`{{`}} $labels.pod {{`}}`}}
+    is taking more than 5 minutes (300 seconds) for a query.
+expr: |-
+  cnpg_backends_max_tx_duration_seconds > 300
+for: 1m
+labels:
+  severity: warning
+  namespace: {{ .namespace }}
+  cnpg_cluster: {{ .cluster }}
+{{- end -}}