Deny access to cloud /login?direct=1 by default

[lvps]

Nginx rule:

            location ~ \.php(?:$|/) {
                # Block direct login: https://github.com/nextcloud/user_saml/issues/284
                if ( $request_uri ~ ^\/+(?:index\.php\/+)?login\?(?:.*&)*direct(?:[&=]|$) ) {
                    return 403;
                }
                ...

But we need a way to disable the block during updates (a script that makes some change with sed?)