If a workflow fails during a test, test fail steps are not exited

[illusional]

FYI @junyk

I believe this is because a SystemExit error is raised (by calling sys.exit) if the workflow / tool fails to run: https://github.com/PMCC-BioinformaticsCore/janis-assistant/blob/fbcefc665a9a23073830acb8f87cc41ea58bcf8f/janis_assistant/management/workflowmanager.py#L595-L598.

These need to be caught separately.