Always set "connect_timeout" when pinging a PostgreSQL instance

Insert "connect_timeout=2" into the connection parameters, if not
explicitly set by the user. This will prevent excessive wait time
for the host operating system to report a connection timeout.

dbutils.h

@@ -465,6 +465,7 @@ int			wait_connection_availability(PGconn *conn, long long timeout);
 
 /* node availability functions */
 bool		is_server_available(const char *conninfo);
+bool		is_server_available_params(t_conninfo_param_list *param_list);
 
 /* monitoring functions  */
 void