We identified several common fields for host inventory schema and these fields include host.id and host.name. add_host_metadata does not overwrite host.name field with #14407 but not host.id.

Things to consider:

1. make add_host_metadata to do nothing if host.* fields already exist.
2. add tests to make sure host.* fields don't get overwritten by add_host_metadata processor.
3. Maybe we should use add_observer_metadata processor instead?

cc @jsoriano