Make tide use workload identity for GCP auth

[fejta]

/assign @cjwagner @michelle192837

ref #15806 #16464

$ gsutil iam get gs://k8s-prow
{
...
    {
      "members": [
        "serviceAccount:[email protected]",
        "serviceAccount:[email protected]"
      ],
      "role": "roles/storage.objectAdmin"
    }
...
}
$ workload-identity/bind-service-accounts.sh k8s-prow us-central1-f prow default tide [email protected]
ALREADY MEMBER: serviceAccount:k8s-prow.svc.id.goog[default/tide] has roles/iam.workloadIdentityUser for [email protected].
+++ kubectl run --rm=true -i --generator=run-pod/v1 --context=gke_k8s-prow_us-central1-f_prow --namespace=default --serviceaccount=tide --image=google/cloud-sdk:slim workload-identity-test-17
DONE: --context=gke_k8s-prow_us-central1-f_prow --namespace=default serviceaccounts/tide acts as [email protected]

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: fejta, michelle192837

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• prow/cluster/OWNERS [fejta,michelle192837]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment