CBQE-1282 disable auto-failover after auto-failvoer phase end

Change-Id: I55ecedc2a8cc7c3e1e1b293eecefb8479276bdf7
Reviewed-on: http://review.couchbase.org/26663
Reviewed-by: Chisheng Hong <chisheng@couchbase.com>
Tested-by: Chisheng Hong <chisheng@couchbase.com>