gke-gcloud-auth-plugin does not honor CLOUDSDK_CONFIG env var

[rustycl0ck]

Maybe not the right repository for filing this bug, but I couldn't find the correct repository. Please move this issue to whatever is the right repository for this.

Problem

As the title says, the gke-cloud-auth-plugin always prints the auth credentials for the default account.
It is impossible to use kubectl CLI with gke-cloud-auth-plugin with two different GKE clusters with two different GCP accounts because the CLOUDSDK_CONFIG environment variable is not honored by the auth plugin.
In addition to this, to choose another account, --account argument must be passed, but the args: parameter in ~/.kube/config is also not honored it seems.

[rustycl0ck]

closing this in favor of kubernetes/cloud-provider-gcp#554