The k8s project recently cut over to the new official k8s.gcr.io
container registry. The descheduler image can now be pulled from
k8s.gcr.io. This is just a new DNS name for the container registry. The
previously documented DNS names for the registry still work, but
require more typing.
Basing this action on push to `chart-*` tags doesn't work: the action itself
creates the new release tag, so trying to push the changes to a tag ends up
with the releaser comparing the changes to themself (and failing).
This also renames the chart from "descheduler" to "descheduler-helm-chart", to
avoid confusion with automated releases.
