CBQE-9:: fix failing rebalance-in test case with compaction

Change-Id: Ifb6149e8df33ad5de8747611c17c4a5adbdbb4db
Reviewed-on: http://review.couchbase.org/39652
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Parag Agarwal <agarwal.parag@gmail.com>
Tested-by: Parag Agarwal <agarwal.parag@gmail.com>