CBQE-0: modified testcfg/xdcr/* to have COUCHBASE_SSH_USER and COUCHBASE_SSH_PASSWORD

Change-Id: I71791aa54ce35ce646bb1a412ecff74cb1844070
Reviewed-on: http://review.couchbase.org/41645
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Aruna Piravi <aruna@couchbase.com>