+++ PROBLEM DESCRIPTION

Ignition override available via `bmac.agent-install.openshift.io/ignition-config-overrides` annotation or `/v2/infra-envs/{infra_env_id}/hosts/{host_id}/ignition` endpoint is being currently ignored for day-2 workers.

By design the ignition provided by the override should be merged with the default template embedded in the service. What happens is that those do work for following

* discovery ISO
* day-1 master
* day-1 worker

and do not work for 

* day-2 worker

The override is transparently ignored so that the user is not aware of it happening.

+++ PROBLEM EXAMPLE

Applying the following override

"""
{
  "config": "{\"ignition\": {\"version\": \"3.1.0\"}, \"storage\": {\"files\": [{\"path\": \"/tmp/example\", \"contents\": {\"source\": \"data:text/plain;base64,aGVscGltdHJhcHBlZGluYXN3YWdnZXJzcGVj\"}}]}}"
}
"""

we have a resulting day-2 worker ignition rendered as

"""
{
  "config": "{\"ignition\":{\"config\":{\"merge\":[{\"source\":\"http://api.test-infra-cluster-fb61821c.redhat.com:22624/config/worker\",\"verification\":{}}],\"replace\":{\"verification\":{}}},\"proxy\":{},\"security\":{\"tls\":{}},\"timeouts\":{},\"version\":\"3.1.0\"},\"passwd\":{},\"storage\":{\"files\":[{\"group\":{},\"overwrite\":true,\"path\":\"/etc/hostname\",\"user\":{\"name\":\"root\"},\"contents\":{\"source\":\"data:,chocobomb-1\",\"verification\":{}},\"mode\":420}]},\"systemd\":{}}"
}
"""

+++ EXPECTED BEHAVIOUR

In the example above we expect the rendered day-2 worker ignition to look as follows

"""
{
  "config": "{\"ignition\":{\"config\":{\"merge\":[{\"source\":\"http://api.test-infra-cluster-fb61821c.redhat.com:22624/config/worker\",\"verification\":{}}],\"replace\":{\"verification\":{}}},\"proxy\":{},\"security\":{\"tls\":{}},\"timeouts\":{},\"version\":\"3.1.0\"},\"passwd\":{},\"storage\":{\"files\":[{\"group\":{},\"path\":\"/tmp/example\",\"user\":{},\"contents\":{\"source\":\"data:text/plain;base64,aGVscGltdHJhcHBlZGluYXN3YWdnZXJzcGVj\",\"verification\":{}}},{\"group\":{},\"overwrite\":true,\"path\":\"/etc/hostname\",\"user\":{\"name\":\"root\"},\"contents\":{\"source\":\"data:,chocobomb-3\",\"verification\":{}},\"mode\":420}]},\"systemd\":{}}"
}
"""