calling `enabled_repos` always forces an errata applicability regeneration
If you restart goferd on a system, errata applicability will be regenerated. This can cause performance issues, especially if you have a large number of hosts.
How reproducible: every time
Steps to Reproduce:
1. register host to Katello, ensure goferd is running
2. restart goferd
3. check tasks list
Actual results: applicability regeneration task is created
Expected results: applicability regeneration should only happen when list of enabled repos changes
Additional info: the task list is the "true" way to check this, but a quick way is to tail /var/log/httpd/foreman-ssl_access_ssl.log on the server and restart goferd on the client. If you see a line like "POST /pulp/api/v2/consumers/actions/content/regenerate_applicability//", it means a regenerate was fired.
Fixes #16209 - do not regenerate applicability if nothing changed
Previously, POSTing to `enabled_repos` from a client would always
result in an applicability generation task running, even if the list of
repos sent up was identical to what Katello already had stored locally.
This caused performance issues, especially if clients were being
Instead, only kick off an applicability generation if the repo list is