This is another and very minor piece of https://github.com/certbot/certbot/issues/9988. We've done nothing to warn/migrate installations using the old `certbot-route53:auth` plugin name and installations like that still exist according to https://gist.github.com/bmw/aceb69020dceee50ba827ec17b22e08a. We could try to warn/migrate these users for a future release or decide it's niche enough that we'll just let it break, but I think it's easy enough to keep the simple shim around. This PR just moves the code raising a deprecation warning into `_internal` as part of cleaning up all deprecation warnings I found in https://github.com/certbot/certbot/issues/9988. I manually tested this with a Certbot config using the `certbot-route53:auth` plugin name and renewal worked just fine.
Amazon Web Services Route 53 DNS Authenticator plugin for Certbot