Update external-dns SA ops
What
https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/6948
Move external-dns SA to new standard.
Why
https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24263
https://ops.gitlab.net/gitlab-com/gl-infra/config-mgmt/-/merge_requests/6948
Move external-dns SA to new standard.
https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24263