Add test for the environment variable LOG_ENV_VARIABLE_NAME

[tkilias]

Background

• We use the run_task function in commons.py for running the root luigi task, which then causes all dependent tasks to run
• The run_task function configures the logging for luigi
• A user can redirect the output to a file with the environment variable LOG_ENV_VARIABLE_NAME
• The environment variable LOG_ENV_VARIABLE_NAME is used here
• Currently, we don't have a test for this function

Acceptance Test

• Add test for the environment variable LOG_ENV_VARIABLE_NAME