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.
I wonder if all the logic should be in this function versus calling destroy_without_content_host.  The reason i ask is that there could be some AR issue with the destroy and we wouldn't want the system destroy to occur if that happens.