Automatic merge from submit-queue
Fix so setup-files don't recreate/invalidate certificates that already exist
Fixes: #23197 and a lot of other DNS and dashboard issues
This is quite critical for `docker`-based users and should be considered as a **cherrypick-candidate** as it makes a lot of people wonder why Dashboard and/or DNS doesn't work. Example: https://github.com/kubernetes/dashboard/issues/374
Earlier when you shut your `docker.md` cluster down and started it again, all ServiceAccounts became invalidated by `setup-files` that happily ran once again and replaced all files. That made `apiserver` and `controller-manager` pick up the new certs (or there was a race condition, they _could_ have picked up the old certs too, but that's unlikely) and the old certs were put into `/var/run/secrets` because the ServiceAccount's Secrets were stored in etcd, which `setup-files` didn't touch.
@fgrzadkowski @huggsboson @thockin @mikedanese @vishh @pwittrock @eparis @bgrant0607
1521aa8a86