Disable automatic login feature when clicking on email confirmation links
This is a patch for issue https://gitlab.com/gitlab-org/gitlab-ce/issues/24411.
GitLab automatically logs a user in when they click on an email confirmation link. This is dangerous as a stolen or sniffed confirmation token can be used to authenticate as that user without knowing a username or password.
This patch needs review as there is likely a reason this behavior was originally enabled.