text: Title: [cluster/gce] Missing --project while adding kubeconfig metadata
  Body: <!-- Please use this template while reporting a bug and provide as much info as possible. Not doing so may result in your bug not being addressed in a timely manner. Thanks!
  
  If the matter is security related, please disclose it privately via https://kubernetes.io/security/
  -->
  
  
  #### What happened:
  
  kube-up tries to add metadata to the wrong project.
  
  https://testgrid.k8s.io/conformance-all#Conformance%20-%20GCE%20-%20master%20-%20kubetest2
  
  https://prow.k8s.io/view/gs/kubernetes-jenkins/logs/ci-kubernetes-gce-conformance-latest-kubetest2/1366974682632294400
  
  ```
  ERROR: (gcloud.compute.instances.add-metadata) Could not fetch resource:
   - Required 'compute.instances.get' permission for 'projects/k8s-infra-prow-build/zones/us-central1-b/instances/kt2-3a058694-7bdc-master'
  ```
  It is trying to add metadata to the prow project running the tests instead of the target project.
  
  This is because 
  
  https://github.com/kubernetes/kubernetes/blob/716a0547206a71ecc6e53f8b970728bc85063a60/cluster/gce/util.sh#L2885
  
  is missing a `--project=${PROJECT}`
  
  #### What you expected to happen:
  kube-up uses the target project to add metadata
  
  #### How to reproduce it (as minimally and precisely as possible):
  Don't set/set a different default project and run cluster/kube-up.
  
  #### Anything else we need to know?:
  
  originally added in https://github.com/kubernetes/kubernetes/pull/77930
  
  kubetest hides the project acquired from boskos under the covers by setting it as the default project
  
  https://github.com/kubernetes/test-infra/blob/81be880b02cc25b7bf77f2ecb9607d0b625460e3/kubetest/main.go#L770
  
  uncovered as part of migration to kubetest2
  
  xref: https://github.com/kubernetes/enhancements/issues/2464
  
  
  /cc @BenTheElder @spiffxp @mm4tt 