Create users in non default backends first
Create users in non default backends first

Most of the time, when people have multiple backends or add a
custom backend, they want to create the users there and not in
the default backend. But since that is registered first, users
were always created there.

Signed-off-by: Joas Schilling <ab43a7c9cb5b2380afc4ddf8b3e2583169b39a02@schilljs.com>

nextcloud/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,nextcloud/server,michaelletzgus/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server,nextcloud/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server