This was missed in the original Ansibling because unlike all the other
settings it does not use an env var to set it. Instead we have to write
a file that the container startup scripts will append to the actual
config.
The comment for this value says it should be a human so we set it to the
root address of the running host which should end up in infra rooter
inboxes.
Change-Id: I235dfcba53c029136c141382920279ab593d1f82
ff733b0975