add namespace to alerts

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

@@ -7,7 +7,7 @@ annotations:
     Replica {{`{{`}} $labels.pod {{`}}`}}
     is failing to replicate
 expr: |
-  cnpg_pg_replication_in_recovery > cnpg_pg_replication_is_wal_receiver_up
+  cnpg_pg_replication_in_recovery{namespace="{{ .namespace }}"} > cnpg_pg_replication_is_wal_receiver_up{namespace="{{ .namespace }}"}
 for: 1m
 labels:
   severity: warning