Moving from fasthosts to nixihost, bit confused by wp_config.php/setup-config.php

The was I normaly misrate sites is:

1. setup a new WordPress site on the target host (so the database etc is set up)
2. note down database settings (wp-config.php)
3. export the database from existing site
4. drop all tables from database target host created
5. import the tables from existing install
6. delete all public_html the files from the target install
7. FTP all the files from existing install
8. change database details in the target WordPress install back to the ones that were setup when I created the new target install (which have now been overittern by FTP I just did)

The last one has got me stumped. The new install uses wp-config.php which has the DB configuration:

define( 'DB_NAME', 'followthe_wp886' );
define( 'DB_USER', 'followthe_wp886' );
define( 'DB_PASSWORD', 'r4]1Q4p7)A-S)x[1' );
define( 'DB_HOST', 'localhost' );
define( 'DB_CHARSET', 'utf8' );
define( 'DB_COLLATE', '' );

But the old one used setup-config.php and used:

$dbname = trim( wp_unslash( $_POST['dbname'] ) );
$uname = trim( wp_unslash( $_POST['uname'] ) );
$pwd = trim( wp_unslash( $_POST['pwd'] ) );
$dbhost = trim( wp_unslash( $_POST['dbhost'] ) );
$prefix = trim( wp_unslash( $_POST['prefix'] ) );

could just set these to the relevent values but I feer an update bay break this ;(.

Or maybe I just put wp-config.php in install and delete setup-config.php?

Any help on unraveling this would be good. Maybe I should

Regards,
Ben