Always pass add_on_name when creating a trial to CDot

What does this MR do and why?

We want to stop relying on the CDot default of "duo_pro" for add_on_name. This MR starts us down that path by always passing the add_on_name explicitly.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

No visual changes

How to set up and validate locally

This can't be easily validated locally b/c you need to also run a CDot instance as such we rely on specs in this area.

Related to #497569 (closed)