Fix Sidekiq ActiveJob integration setup

* .connect on a Redis connection wasn't valid
* Reset logger after we're done testing for redis connection to avoid
  "closed stream" error when starting server for real from a fork

I'm not sure when this started happening, since these tests don't fail Travis (is that intentional?) even though they should work fine there.
I don't think so either, but it's being done in most other places in ActiveJob.