raft: replication test: elect_new_leader in raft_cluster
raft: replication test: elect_new_leader in raft_cluster

Move elect_new_leader to raft_cluster.

Signed-off-by: Alejo Sanchez <004be06a28e38b437b038f9b5c0b9f5758b792e9@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla