kubernetes/gke: skip API tests in short mode

Updates golang/go#30612

Change-Id: I752c57f8631025f1784951e701340d2c21ee277c
Reviewed-on: https://go-review.googlesource.com/c/build/+/165777
Reviewed-by: Bryan C. Mills <bcmills@google.com>
diff --git a/kubernetes/gke/gke_test.go b/kubernetes/gke/gke_test.go
index 0a79a4d..1da2a47 100644
--- a/kubernetes/gke/gke_test.go
+++ b/kubernetes/gke/gke_test.go
@@ -115,6 +115,9 @@
 }
 
 func foreachCluster(t *testing.T, fn func(*container.Cluster, *kubernetes.Client)) {
+	if testing.Short() {
+		t.Skip("skipping in short mode")
+	}
 	if !metadata.OnGCE() {
 		t.Skip("not on GCE; skipping")
 	}