Leader will try to let removed nodes know that they have been removed
One node in the cluster has to be told that it has leadership potential. Only then can it become a leader.
At that point, the idea of leadership will spread and any node can become leader. But this prevent a situation where bringing up a new node creates its own separate cluster.
Changing the behavior of a node that only if it is marked by a leader or is contacted by a leader is it eligible for leadership
Fixing tests