drop KUBE_TIMEOUT in test/cmd/kubeadm.sh

	As runyontr remarked in test/cmd/kubeadm.sh: when
	kubernetes/kubeadm#1430 is closed,
	KUBE_TIMEOUT can be removed.

test/cmd/kubeadm.sh

@@ -28,12 +28,9 @@ run_kubeadm_tests() {
   # comment this out to save yourself from needlessly building here.
   make -C "${KUBE_ROOT}" WHAT=cmd/kubeadm
 
-  #TODO(runyontr): Remove the KUBE_TIMEOUT override when 
-  # kubernetes/kubeadm/issues/1430 is fixed
   make -C "${KUBE_ROOT}" test \
   WHAT=k8s.io/kubernetes/cmd/kubeadm/test/cmd \
-  KUBE_TEST_ARGS="--kubeadm-path '${KUBEADM_PATH}'" \
-  KUBE_TIMEOUT="--timeout=600s"
+  KUBE_TEST_ARGS="--kubeadm-path '${KUBEADM_PATH}'"
   set +o nounset
   set +o errexit
 }