CBQE-983: tidy up upgrade tests for windows

adaptation of existing upgrade tests for windows

Change-Id: Ibe49de8a63066b6238ed2e1b2403f518b5ba46d3
Reviewed-on: http://review.couchbase.org/24578
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Ketaki Gangal <ketakigangal@gmail.com>