Ensure get_pg_settings() returns false if parameter not found

Previously, if e.g. a non-superuser connection is used to get a value
like `data_directory`, which is available to superusers only, it
would return true.

dbutils.c

@@ -504,7 +504,7 @@ get_pg_setting(PGconn *conn, const char *setting, char *output)
 	char		sqlquery[QUERY_STR_LEN];
 	PGresult   *res;
 	int			i;
-	bool        success = true;
+	bool        success = false;
 
 	sqlquery_snprintf(sqlquery,
 					  "SELECT name, setting "

repmgr.c

@@ -3697,7 +3697,7 @@ do_standby_switchover(void)
 	/* the remote server is the primary to be demoted */
 	char	    remote_conninfo[MAXCONNINFO] = "";
 	char	    remote_host[MAXLEN];
-	char        remote_data_directory[MAXLEN];
+	char        remote_data_directory[MAXPGPATH] = "";
 	int         remote_node_id;
 	char        remote_node_replication_state[MAXLEN] = "";
 	char        remote_archive_config_dir[MAXLEN];