kubeadm uses LeaseEndpointReconcilerType as import from
k8s.io/kubernetes/pkg/master/reconcilers. However, this pull a huge
load of extra dependencies (among which
pkg/client/clientset_generated/internalclientset). The solution is
to copy this string constant locally in kubeadm.
Signed-off-by: Rostislav M. Georgiev <rostislavg@vmware.com>