After leader is isolated, new leader is elected too slowly

This is affecting CSIT results at the node which ends up being a follower in the majority partition, so this might be related to AAA-130.

This prevents testing a scenario when isolation is short enough so that client does not time out.

In the recent test, it took 44 seconds to confirm both members agree on the new leader, and ODL took [0] almost 5 second to respond to the final request.

Karaf.log [1] shows several suspicious lines between 06:23:51,346 and 06:24:49,542, but it is not clear to me what causes the process to take this long.

[0] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/684/archives/log.html.gz#s1-s33-t1-k2-k11-k2-k1-k1-k6-k2-k1-k5-k1-k3-k1
[1] https://logs.opendaylight.org/releng/jenkins092/controller-csit-3node-clustering-only-carbon/684/archives/odl3_karaf.log.gz