Some service steps require an IPA ramdisk. Its image is normally provided by ICC through a PreprovisioningImage resource that BMO creates.

However, PreprovisioningImages are not created for hosts enrolled as ExternallyProvisioned, which causes Ironic to try using the default ramdisk, which is not defined for OpenShift.

Reproducer (example):

1. Provision any BareMetalHost from a cluster (can be an extra worker in dev-scripts)
2. Detach and then delete the host.
3. Re-create the host setting externallyProvisioned to true.
4. Once the host's state is "externally provisioned", try to use the servicing flow with HFS (create a HUP, modify HFS, reboot).
5. Servicing quickly fails.