CBQE-0: fix unixdcr tests with different sizes due to VM's limitations to load lesser items

Change-Id: Ibbaf81f295274d7828dc55c93c1100b64cbd14ef
Reviewed-on: http://review.couchbase.org/41355
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>