Fix behavior of last 3 hours test mode switch (EXPOSUREAPP-3179) (#1375)

* Improve test readability, create helper methods for locations,days,hours.

* Prepare better test data that allow for future 3+hours tests.

* Fix last 3 hours mode downloading key package files from yesterday instead of today,
due to being based of the latest server index day files. We need to get them for the latest day index file,
plus 1 day.

* Fix hour formatting, server uses hour format without leading zeros

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>