repmgrd: ensure PQfinish() always executed on failed connections in NodeInfoLists

clear_node_info_list() will clean up any remaining active connections,
but we need to ensure all failed connections are cleaned up at the point
of failure to prevent leaks.

Per report in GitHub #643.

repmgrd-physical.c

@@ -1853,6 +1853,7 @@ monitor_streaming_standby(void)
 							if (PQstatus(cell->node_info->conn) != CONNECTION_OK)
 							{
 								log_debug("unable to connect to %i ... ", cell->node_info->node_id);
+								close_connection(&cell->node_info->conn);
 								continue;
 							}
 
@@ -2470,6 +2471,7 @@ monitor_streaming_witness(void)
 						if (PQstatus(cell->node_info->conn) != CONNECTION_OK)
 						{
 							log_debug("unable to connect to %i ... ", cell->node_info->node_id);
+							close_connection(&cell->node_info->conn);
 							continue;
 						}
 
@@ -3585,6 +3587,8 @@ notify_followers(NodeInfoList *standby_nodes, int follow_node_id)
 					 cell->node_info->node_name,
 					 cell->node_info->node_id);
 
+			close_connection(&cell->node_info->conn);
+
 			cell->node_info->conn = establish_db_connection(cell->node_info->conninfo, false);
 		}
 
@@ -3595,6 +3599,7 @@ notify_followers(NodeInfoList *standby_nodes, int follow_node_id)
 						cell->node_info->node_id);
 			log_detail("\n%s", PQerrorMessage(cell->node_info->conn));
 
+			close_connection(&cell->node_info->conn);
 			continue;
 		}
 
@@ -4189,6 +4194,7 @@ do_election(NodeInfoList *sibling_nodes, int *new_primary_id)
 
 		if (PQstatus(cell->node_info->conn) != CONNECTION_OK)
 		{
+			close_connection(&cell->node_info->conn);
 			continue;
 		}