CBQE-0: Re-strucutre xdcrbasetests.py to group similar function together

Change-Id: Ibe9f61275b6a0bf145ba90ace28758565288c1a8
Reviewed-on: http://review.couchbase.org/34491
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>