wp-config-sample.php file from the root of the WordPress application can be considered as a good security practice or it does not make any difference for security?
wp-config-sample.php doesn't make any difference: it doesn't contain anything important, it doesn't run anything by itself and nothing in WordPress use any configuration parameters from it.
What's more important is to avoid having any copies of the actual
wp-config.php with a different file extension that wouldn't get treated as a PHP script, revealing the contents including database password. E.g. some editors could leave such backups.