CBQE-0: added warm parameter in the tests for conf/py-xdcr-bidirectional.conf

Change-Id: I8cb75b6f92115a8a68a67181cc08e1208de9336b
Reviewed-on: http://review.couchbase.org/35438
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>