CBQE-0 :: remove unused code from failover tests

Change-Id: I6c7b6229463b517d13de83c3c92f2570c96d0fdd
Reviewed-on: http://review.couchbase.org/40186
Reviewed-by: Ashvinder Singh <ashvinder@couchbase.com>
Tested-by: buildbot <build@couchbase.com>