Bind the gerrit service account to a GCP one

[fejta]

ref #202

/assign @Katharine @chases2

test-infra$ experiment/workload-identity/enable-workload-identity.sh oss-prow us-west1-a prow
++ gcloud beta container clusters describe prow '--format=value(workloadIdentityConfig.identityNamespace)' --project=oss-prow --zone=us-west1-a
++ gcloud beta container node-pools list --cluster=prow '--format=value(name,config.workloadMetadataConfig.nodeMetadata)' --project=oss-prow --zone=us-west1-a
Nothing to do

After merging I can run:

test-infra$ experiment/workload-identity/bind-service-accounts.sh oss-prow us-west1-a prow default gerrit [email protected]
Service account has wrong/missing annotation, please declare the following to default/gerrit in gke_oss-prow_us-west1-a_prow:
{"metadata": {"annotations": "iam.gke.io/gcp-service-account": "$gcp_service_account"}}

[fejta]

Can I get a review here?

[google-oss-robot]

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