ctdb-recoverd: Drop leader validation

ctdb-recoverd: Drop leader validation

The introduction of the leader broadcast timeout provides an
alternative to the current leader validation.  Using the leader
broadcast may not be as fast but it is more correct.

When the leader node is stopped or banned, the only way of triggering
an election is currently to fetch the leader's node map to check
whether the it is still active.  This is because the leader will no
longer push the node map to other nodes.  However, having all nodes
fetch the node map from an inactive leader may be unreliable.

Most of the other cases are also handled more reliably by the leader
broadcast timeout.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>