Spamcheck: Remove check for production env for encrypting communication in favor of url scheme check

Followu-up to #346397 (closed)

This issue is simply to remove the check that automatically enables grpc encrypted communications when running on production. #346397 (closed) enabled support for a Spamcheck URL with a tls scheme to explicitly force it to encrypt the channel. That issue kept the production check so that rollout could be done without forcing gitlab to use an unencrypted channel.

This issue needs to be rolled out only after the URL on the admin panel has been updated to have a tls scheme.