Windows Job Supervisor: stagger flapping intervals
Windows Job Supervisor: stagger flapping intervals

This will hopefully reduce some of the flackiness around the flapping
tests by having them die at staggered intervals.

[#148915345](https://www.pivotaltracker.com/story/show/148915345)

cloudfoundry/bosh-agent,mattcui/bosh-agent,mattcui/bosh-agent,gu-bin/bosh-agent,cloudfoundry/bosh-agent,gu-bin/bosh-agent,gu-bin/bosh-agent,mattcui/bosh-agent