updated unit tests for ScrubEphemeralDisk
updated unit tests for ScrubEphemeralDisk

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