Improve the existing DAP not available empty state.

What does this MR do and why?

This improves the existing DAP not available empty state.

• Implement the "cannot start" a trial empty state

  This updates the DAP empty state component to handle the case where the user does not have access to DAP and cannot start a trial.

• Add instrumentation to the DAP not available empty state

  Adds tracking for the following events:

  • User sees the empty state
  • User clicks on the "Start a Free Trial" link
  • User clicks on the "Learn more" link

References

• https://gitlab.com/gitlab-org/gitlab/-/work_items/588287+

Screenshots or screen recordings

Before	After
The panel does not appear

How to set up and validate locally

1. Enable the dap_onboarding_empty_states feature flag: https://gdk.test:3443/rails/features/dap_onboarding_empty_states
2. Create a new free account and sign in.
3. Navigate to a project/group the user has limited access to.

• Observe that that the AI panel is available and expanded by default.

MR acceptance checklist

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

Related to #588287