Ansible Callback when Running from Foreman UI

I have Foreman 1.14.1, and Ansible 2.3 installed on Foreman host.
/etc/ansible/ansible.cfg is configured to use the Foreman callback. When I
run Ansible from the Foreman UI, however, it is attempting to use the
default callback configuration.

How do I set the environment variables that will be used by the task
executor that runs ansible when triggered from the UI?

I've tried exporting the variables in /etc/default/foreman-tasks, but this
doesn't seem to work.

Any other thoughts?