CBQE-0: adding 30 second sleep after create buckets in XDCR tests, these changes will revert once MB-9707 will be fixed

Change-Id: I4e226f90b21fe2be0edeec10e06be55bb63e222f
Reviewed-on: http://review.couchbase.org/31811
Reviewed-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>
Tested-by: Sangharsh Agarwal <sangharsh.agarwal@globallogic.com>