[services-ng] add timeout to postgresql max_long_tx case

Change-Id: I665064ea840bd3e2f438acbdfbf22dd3be970738
Reviewed-on: http://reviews.cloudfoundry.org/13130
Tested-by: CI Master <cf-ci@rbcon.com>
Reviewed-by: Frank Lu <flu@vmware.com>
Reviewed-by: Michael Zhang <zhangcheng@rbcon.com>
Reviewed-by: Figo Feng <ffeng@vmware.com>