Student profile CSV background task tech debt

TNL-525

These 4 commits address 4 fairly small instances of technical debt that @nasthagiri and I came across while working on the backgroundify student profile CSV story.

@jimabramson @nasthagiri please review.

@cahrens FYI
For ongoing code maintenance, try to keep each variable localized to the code that actually needs it.
Also, is it necessary to define a one-time use `start_time` variable?