use a separate virtualenv for ora for jenkins tests

playbooks/edx_jenkins_tests.yml

@@ -6,6 +6,8 @@
     migrate_db: True
     mysql5_workaround: True
     ansible_ssh_private_key_file: /var/lib/jenkins/continuous-integration.pem
+    # use a separate virtualenv for ora
+    ora_venv_dir: /opt/wwc/virtualenvs/ora
   vars_files:
     - "{{ secure_dir }}/vars/edxapp_ref_users.yml"
     - "{{ secure_dir }}/vars/edxapp_sandbox.yml"