Function run 

pub async fn run(
    process: WorkerProcess,
    db_pool: PgPool,
    app_configuration: ApplicationConfiguration,
    still_running_message: &str,
) -> CreditRegistrationResult<()>

Runs the phases process owns until SIGTERM or Ctrl-C. Each phase loops on its own, so an hour-long call in one does not hold up the others. On shutdown no phase starts another iteration, and the function returns once the iterations already running have finished.