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.
Merge pull request #4666 from parthaa/host-delete

Fixes #7446/bz1140653 - Host delete dynflowed