Add exact-events guards for remaining AiTracking features

What does this MR do and why?

ee/spec/lib/gitlab/tracking/ai_tracking_spec.rb has a per-feature 'contains exact events' guard that asserts the exact event set registered for a feature, so adding or removing an event trips the spec and prompts the author to weigh materialized-view impact.

Only 4 of the 9 registered features had this guard. This adds it for the 5 that were missing (chat, troubleshoot_job, mcp, fix_pipeline, duo_workflow), so every feature in the registry is covered. Test-only, no behavior change.

Surfaced during Duo AiTracking audit work (#567159), where the missing guard for a newly added feature was noted in review.

How to set up and validate locally

bundle exec rspec ee/spec/lib/gitlab/tracking/ai_tracking_spec.rb

EE: true