SIG Auth: complete migration to kubernetes.io mailing lists

This issue outlines action items needed to migrate SIG Auth mailing lists to kubernetes.io.

/sig auth
/cc [@kubernetes/sig-auth-leads](https://github.com/orgs/kubernetes/teams/sig-auth-leads)
/assign

### Context

- Existing SIG Auth mailing list:
https://groups.google.com/g/kubernetes-sig-auth/

- New mailing list:
https://github.com/kubernetes/k8s.io/blob/main/groups/sig-auth/groups.yaml#L41

- Example notification: https://groups.google.com/a/kubernetes.io/g/sig-apps/c/GeL5shs1nRY/m/9Lybuv8lAQAJ?utm_medium=email&utm_source=footer

- Instructions: https://kubernetes.slack.com/archives/CD6LAC15M/p1732010989229329?thread_ts=1731973436.629349&cid=CD6LAC15M

### Action items

1. Migrate users to the new mailing list (from Slack):

1. SIG exports mailing list as CSV
2. Import mailing list a google sheet
3. filter columns and delete all rows that have a bounce status
4. filter columns and remove anyone that has the OWNER role (they'll have that already)
5. create new sheet (new tab) - add these columns
Group Email [Required] Member Email Member Type Member Role
6. copy email column from exported list to the Member Email column
7. For every row the group email should be the name of the mailing list e.g. [sig-cluster-lifecycle@kubernetes.io](mailto:sig-cluster-lifecycle@kubernetes.io), Member Type should be USER Member Role should be MEMBER
8. Save this as a csv
9. here steering should import the prepared CSV
10. remove [calendar@kubernetes.io](mailto:calendar@kubernetes.io) from old list (this will prevent duplicate events appearing on the calendar)

2. Update google docs with the new mailing list links and permissions

3. Update all calendar events to invite new mailing list

4. update sigs.yaml and other mentions: https://github.com/search?type=code&q=kubernetes-sig-network%40googlegroups.com+org%3Akubernetes

5. send comms to mailing list with notification of new list, lock the list, prevent new members from joining or sending email.