CBQE-0: decrease timeout in xdcr tests after load phase

to speed up buildbot

Change-Id: I753e8f5d90f7de8cc2925b4b6ecaff6b6561e2d5
Reviewed-on: http://review.couchbase.org/31359
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>