Fixes #7446/bz1140653 - Host delete dynflowed

Previously when a host got deleted in foreman either via UI or API
the content_host active record would get deleted but NOT the backend
like candlepin or pulp consumer information. This commit aims to fix that
by making foreman's delete host call use katello's consumer delete dynflow.
Awesome, thanks! This rake task works fine after adding `next if system.is_a? Katello::Hypervisor` here

I have some hypervisors in my Katello instance (this virt-who subscription tracking stuff), and this breaks it because you can't do any pulp actions on them, and actually deleting them in Candlepin like a normal consumer causes a 401 Gone error.