Make it possible to remove "Your site is not yet registered" message in Site Administration

We have a deployment pipelines with several non-production Moodle LMS sites (e.g. dev, qa, staging) which will never be registered. As a Moodle Site Administrator, I would like to be able to remove the persistent "Your site is not yet registered" message and the "Register your site" button which appear near the top of the page in Site Administration on non-production sites.

After applying the attached commit (coming soon), Admins would be able to remove this message by adding the following line to their Moodle LMS site's config.php file:

$CFG->neverregister = true;