Sometimes, QoS bandwidth constraint does not work on HTCondor job

[lostwinder]

In project_oriented mode, when both GridFTP file transfer and HTCondor job are running:

1. GridFTP grabs most of the bandwidth and only when GridFTP file transfer finishes, HTCondor job can take back the bandwidth in queue.
2. Sometimes, when HTCondor job has not been able to get the bandwidth back (since GridFTP file transfer is ongoing) for a long time, the bandwidth constraint on HTCondor job does not hold and the bandwidth goes as high as possible to the maximum. This is one bug needs to be figured out.