Deprecate using gencred and switch to using Google principals to authenticate to GKE clusters

[upodroid]

The new gke auth plugin doesn't store access tokens in the kubeconfig file.

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: SOME CERT
    server: https://34.90.233.66
  name: gke_mahamed_europe-west4_dev
contexts:
- context:
    cluster: gke_mahamed_europe-west4_dev
    user: gke_mahamed_europe-west4_dev
  name: gke_mahamed_europe-west4_dev
current-context: gke_mahamed_europe-west4_dev
kind: Config
preferences: {}
users:
- name: gke_mahamed_europe-west4_dev
  user:
    exec:
      apiVersion: client.authentication.k8s.io/v1beta1
      command: gke-gcloud-auth-plugin
      installHint: Install gke-gcloud-auth-plugin for use with kubectl by following
        https://cloud.google.com/blog/products/containers-kubernetes/kubectl-auth-changes-in-gke
      provideClusterInfo: true

Intree gcp plugin used to do the following which wasn't great.

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: SOME CERT
    server: https://34.90.233.66
  name: gke_mahamed_europe-west4_dev
contexts:
- context:
    cluster: gke_mahamed_europe-west4_dev
    user: gke_mahamed_europe-west4_dev
  name: gke_mahamed_europe-west4_dev
current-context: gke_mahamed_europe-west4_dev
kind: Config
preferences: {}
users:
- name: gke_mahamed_europe-west4_dev
  user:
    auth-provider:
      config:
        access-token: REDACTED
        cmd-args: config config-helper --format=json
        cmd-path: /Users/REDACTED/google-cloud-sdk/bin/gcloud
        expiry: "2022-11-30T15:48:48Z"
        expiry-key: '{.credential.token_expiry}'
        token-key: '{.credential.access_token}'
      name: gcp

Related to #27896

/sig testing
/sig k8s-infra

[ameukam]

cc @chaodaiG @cjwagner

[k8s-triage-robot]

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/lifecycle stale

[upodroid]

/priority important-longterm

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle rotten
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten

[BenTheElder]

@upodroid [edit: is this] still important with the migration? (not sure what we settled on in k8s-infra)

[upodroid]

It is important, Argo is configured to access clusters using gke-auth plugin and we want prow to do the same as well