If enabled, rabbit is required for all ironic services, so it makes
no sense to only configure it when API is enabled. This seems to
break multinode grenade, since `is_service_enabled ir-api` returns
false on the subnode. Try to configure the RPC backend in all cases
when IRONIC_RPC_TRANSPORT is "oslo" (not JSON RPC).
Also move the automated_clean option to the conductor where it belongs.
Change-Id: I6e046c6b6e1e4c0ca7bfd5fb9ce5892c0298fb78