Summary:
This tests checks the correctness of a leader election process when its
decoupled from log replication. In other words, in this test we do not change
the state of the database, i. e., the Raft log remains empty.
The test proceeds as follows for clusters of size 3 and 5:
1. Start a random subset of workers in the cluster
2. Check if the leader has been elected
3. Kill all living workers
4. GOTO 1 and repeat 10 times
Reviewers: msantl
Reviewed By: msantl
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D2105
