* runner: Expose dind runner dockerd logs via stdout/stderr
We've been letting supervisord to run dockerd within the dind runner container presuming it would avoid producing zombie processes. However we used dumb-init to wrap supervisord to wrap dockerd. In this picture supervisord might be unnecessary and dumb-init is actually a correct pid 0 for containers.
Rmoving supervisord removes this unnecessary complexity, while saving a little memory, and more importantly logs from dockerd is exposed via stdout/stderr of the container for easy access from kubectl-logs, fluentd, and so on.
