Currently, the `add_hosts_to_hbi` function needs to be different to work for the host-inventory main branch/current latest image and the active branch `add-kessel-client`/custom image we are working on for hbi migration.

We are hoping we can make an upstream change to insights-host-inventory so that the same script function can be used for both. (FYI wscalf@redhat.com.) Once that is done, we will be able to contribute the latest add hosts code back to the main branch of the deployer. This Jira is to do this tidy-up work.