Remove clusterName from nodepool.yaml (#427)

The clusterName is no longer required here and just causes errors when trying to deploy Kubeflow on GCP. 
Remove this line:

```clusterName: "PROJECT/LOCATION/KUBEFLOW-NAME" # kpt-set: ${gcloud.core.project}/${location}/${name}```

kubeflow/common/cluster/upstream/nodepool.yaml

@@ -15,7 +15,6 @@
 apiVersion: container.cnrm.cloud.google.com/v1beta1
 kind: ContainerNodePool
 metadata:
-  clusterName: "PROJECT/LOCATION/KUBEFLOW-NAME" # kpt-set: ${gcloud.core.project}/${location}/${name}
   name: KUBEFLOW-NAME-cpu-pool-v1 # kpt-set: ${name}-cpu-pool-v1
 spec:
   initialNodeCount: 2