Remove part of api test

This test is trying to confirm behavior when an api cannot be loaded.
It is no longer possible for an AssessmentWorkflow to have been created
without going through __init__(), so the latter part of this test is
now trying to confirm assumptions about an impossible state.

I recommend we just remove it.

openassessment/workflow/test/test_api.py

@@ -361,16 +361,6 @@ class TestAssessmentWorkflowApi(CacheResetTest):
         with self.assertRaises(AssessmentWorkflowInternalError):
             workflow_api.create_workflow(submission['uuid'], ['self'], ON_INIT_PARAMS)
 
-        AssessmentWorkflow.objects.create(
-            submission_uuid=submission['uuid'],
-            status=AssessmentWorkflow.STATUS.waiting,
-            course_id=ITEM_1['course_id'],
-            item_id=ITEM_1['item_id']
-        )
-
-        with self.assertRaises(AssessmentApiLoadError):
-            workflow_api.update_from_assessments(submission['uuid'], {})
-
     def test_cancel_the_assessment_workflow(self):
         # Create the submission and assessment workflow.
         submission = sub_api.create_submission(ITEM_1, ANSWER_1)