CBQE-2411: adding code to new xdcr base tests

Change-Id: I204cc4a9aa20a0ba2a19e00ff09f7825860b48a8
Reviewed-on: http://review.couchbase.org/41603
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Aruna Piravi <aruna@couchbase.com>