test: ensure expected files and variables exist

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Overview

This addresses part of !1363 (comment 2796427462) - unit tests (run via poetry run pytest -m 'unit_test' congregate/tests/) now pass from the first go without having to touch log files and environment variables.

Tasks

• Update docs if needed (workflow, runbooks, README, migration metrics, etc.)

I don't think it needs an update in the docs.

Acceptance Criteria

• Existing UTs pass locally. If you need help updating any tests, refer to our writing tests documentation