CBQE-1661: added xdcr tests for data_size 1 Character, 1M, 10M

Change-Id: I18bdfcd15c98a878b32a37d03ec731ea1fe0dad8
Reviewed-on: http://review.couchbase.org/41083
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Aruna Piravi <aruna@couchbase.com>