Fix logging in Duo Workflow Service

When Duo Agent platform is relased for self-hosted Duo customers, we want to make sure that we follow the same kind of logging we do for AI Gateway.

That is:

• value of expanded_ai_logging FF is immaterial - expanded_ai_logging is only meant for use on .com and should not affect self-managed and self-hosted Duo instances.
• On self-hosted Duo instances, what is used for expanded logging is the instance setting - ::Ai::Setting.instance&.enabled_instance_verbose_ai_logs. So we should be using the same key for self-hosted DWS's expanded logging too.

See existing condition used for expanded logging in AIGW here