feat: use FQDN instead of pod IP for Patroni connect_address

This change fixes Citus metadata sync issues where nodes register in
pg_dist_node with ephemeral pod IPs. When pods restart and get new IPs,
the stale IPs in pg_dist_node cause metadata synchronization to fail.

Changes:
- PatroniConfigMap.java: Added PATRONI_CONFIG_SERVICE_NAME and
  PATRONI_POD_NAMESPACE env vars, changed PATRONI_POSTGRESQL_CONNECT_ADDRESS
  to use FQDN pattern
- PatroniEnvironmentVariables.java: Changed PATRONI_RESTAPI_CONNECT_ADDRESS
  to use FQDN pattern
- start-patroni.sh: Changed connect_address in restapi and postgresql
  sections to use the FQDN-based env vars instead of PATRONI_KUBERNETES_POD_IP

The FQDN pattern used is:
${POD_NAME}.${PATRONI_CONFIG_SERVICE_NAME}.${PATRONI_POD_NAMESPACE}.svc.cluster.local

This ensures stable node registration that survives pod restarts.

Author: marcelozani

stackgres-k8s/src/operator/src/main/java/io/stackgres/operator/conciliation/factory/cluster/patroni/PatroniConfigMap.java

@@ -117,8 +117,12 @@ public static String name(ClusterContext clusterContext) {
         .map(Object::toString)
         .orElse("60"));
     data.put("PATRONI_POSTGRESQL_LISTEN", (isEnvoyDisabled ? "0.0.0.0,[::]:" : "127.0.0.1,[::1]:") + EnvoyUtil.PG_PORT);
+    // Use FQDN instead of POD_IP for stable node registration in Citus pg_dist_node
+    data.put("PATRONI_CONFIG_SERVICE_NAME", PatroniUtil.configName(cluster));
+    data.put("PATRONI_POD_NAMESPACE", cluster.getMetadata().getNamespace());
     data.put("PATRONI_POSTGRESQL_CONNECT_ADDRESS",
-        "${POD_IP}:" + (isEnvoyDisabled ? EnvoyUtil.PG_PORT : EnvoyUtil.PG_REPL_ENTRY_PORT));
+        "${POD_NAME}.${PATRONI_CONFIG_SERVICE_NAME}.${PATRONI_POD_NAMESPACE}.svc.cluster.local:"
+        + (isEnvoyDisabled ? EnvoyUtil.PG_PORT : EnvoyUtil.PG_REPL_ENTRY_PORT));
 
     data.put("PATRONI_RESTAPI_LISTEN", "*:" + EnvoyUtil.PATRONI_PORT);
     data.put("PATRONI_POSTGRESQL_DATA_DIR", ClusterPath.PG_DATA_PATH.path());

stackgres-k8s/src/operator/src/main/java/io/stackgres/operator/conciliation/factory/cluster/patroni/PatroniEnvironmentVariables.java

@@ -202,7 +202,8 @@ && getPostgresFlavorComponent(cluster) == StackGresComponent.BABELFISH) {
             .build(),
             new EnvVarBuilder()
             .withName("PATRONI_RESTAPI_CONNECT_ADDRESS")
-            .withValue("${POD_IP}:" + EnvoyUtil.PATRONI_PORT)
+            // Use FQDN instead of POD_IP for stable node registration in Citus pg_dist_node
+            .withValue("${POD_NAME}.${PATRONI_CONFIG_SERVICE_NAME}.${PATRONI_POD_NAMESPACE}.svc.cluster.local:" + EnvoyUtil.PATRONI_PORT)
             .build());
 
     return ImmutableList.<EnvVar>builder()

stackgres-k8s/src/operator/src/main/resources/templates/start-patroni.sh

@@ -254,15 +254,15 @@ fi
   - 'host replication ${PATRONI_REPLICATION_USERNAME} 0.0.0.0/0 md5'
   - 'host replication ${PATRONI_REPLICATION_USERNAME} ::/0 md5'
 restapi:
-  connect_address: '${PATRONI_KUBERNETES_POD_IP}:8008'
+  connect_address: '${PATRONI_RESTAPI_CONNECT_ADDRESS}'
   listen: "*:8008"
 postgresql:
   use_slots: true
   use_pg_rewind: true
   remove_data_directory_on_rewind_failure: true
   use_unix_socket: true
   use_unix_socket_repl: true
-  connect_address: '${PATRONI_KUBERNETES_POD_IP}:5432'
+  connect_address: '${PATRONI_POSTGRESQL_CONNECT_ADDRESS}'
   listen: 0.0.0.0,[::]:5432
   pg_ctl_timeout: $PATRONI_PG_CTL_TIMEOUT
   authentication: