relayhost change not reflected

When setting or unsetting the relayhost in de server config of a specific server, this change isn't reflected in the postfix main.cf config.

The problem is within the new settings object which is always the same as the old one

https://git.ispconfig.org/ispconfig/ispconfig3/-/blob/develop/server/plugins-available/postfix_server_plugin.inc.php#L78

When changed to:

$new_ini_data = $app->ini_parser->parse_ini_string($data['new']['config']);
$mail_config = $new_ini_data['mail'];

everything works as expected.