raft: replication test: fix election connectivity
raft: replication test: fix election connectivity

If a leader was already disconnected the election of a new leader could
re-connect. Save original connectivity and restore it when done electing
new leader.

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

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