We are now publishing nameserver images to tailscale/k8s-nameserver,
so we can start defaulting the images if users haven't set
them explicitly, same as we already do with proxy images.
The nameserver images are currently only published for unstable
track, so we have to use the static 'unstable' tag.
Once we start publishing to stable, we can make the operator
default to its own tag (because then we'll know that for each
operator tag X there is also a nameserver tag X as we always
cut all images for a given tag.
Updates tailscale/tailscale#10499
Signed-off-by: Irbe Krumina <irbe@tailscale.com>
b5dbf155b1