CBQE-0 :: fix bug due to cleanup and call to verify unacked bytes, should not be present in tear down

Change-Id: I1e09d45d7765bf649cc8bf2700ab9893fb56415a
Reviewed-on: http://review.couchbase.org/38146
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Parag Agarwal <agarwal.parag@gmail.com>
Tested-by: Parag Agarwal <agarwal.parag@gmail.com>