Writing to a hostPath from a non-root container requires file
ownership changes, which is difficult to roll out today. See
discussion in #8454
We were primarily using the logfile for e2e diagnostics, so we're
going to look into collecting the information via other means instead.
We also haven't yet shipped this logfile in a released version (though
we have shipped it in beta releases)
We then `docker load` it when using a KOPS_BASE_URL.
This should simplify the development process (particularly once we
also do this for dns-controller; at that point we won't need a
registry at all).
This should also fix the problems in CI, where the kops-controller
image isn't available. We've been getting away with testing with the
previous version for dns-controller, which changes pretty slowly. But
that's not a good idea for kops-controller, which is likely to be more
critical and evolve more rapidly.