Looks like you found a bug, thanks for reporting it. The installer stopped configuring that url because it was Pulp 2 related, but Katello is still actually using it.
Here’s a workaround that should work for now:
Go to /etc/foreman/plugins/katello.yaml and add the following config under :katello::
I believe it’s a separate issue because, on my machine with the same localhost bug, I can access both my http and https repositories.
Do the http repositories time out if you try curl them from your Katello server itself?
When you hit the http endpoint, do you see any logs pop up in /var/log/messages from pulpcore-content? Or perhaps any logs in /var/log/httpd/foreman_access.log ?