XQueue wasn't using this argument and it was removed

It now throws an error from Django if you pass in the unused parameter.

playbooks/roles/xqueue/templates/xqueue_consumer.conf.j2

 [program:xqueue_consumer]
 
-command={{ xqueue_venv_bin }}/django-admin.py run_consumer --pythonpath={{ xqueue_code_dir }} --settings=xqueue.{{ XQUEUE_SETTINGS }} $WORKERS_PER_QUEUE
+command={{ xqueue_venv_bin }}/django-admin.py run_consumer --pythonpath={{ xqueue_code_dir }} --settings=xqueue.{{ XQUEUE_SETTINGS }}
 
 user={{ common_web_user }}
 directory={{ xqueue_code_dir }}