delete artifact failure after failure in workflow

[antgonza]

There is an error when you try to delete an artifact after a workflow fails:

ValueError: Error running SQL query:
Query: DELETE FROM qiita.processing_job
                         WHERE processing_job_id IN %s
Arguments: [('564731e7-a3f9-4ab9-afd1-553ed947eeed', '40630b19-7b94-488c-8763-7e8e40fc8baf')]
Error: update or delete on table "processing_job" violates foreign key constraint "fk_processing_job_workflow_root_wf" on table "processing_job_workflow_root"
DETAIL:  Key (processing_job_id)=(40630b19-7b94-488c-8763-7e8e40fc8baf) is still referenced from table "processing_job_workflow_root".

[antgonza]

@josenavas did you fix this one?

[josenavas]

Here: #1806 I forgot to add the fixes thing.