feat(AI): add section on CTA hierarchy

What does this MR do?

This MR is a follow-up from a comment on !3954 (merged).

Users have the ability to disable AI features on the instance, group, and/or project. This functionality was added after customer feedback. Normally, when a feature is not available, we do not show anything in the UI.

The MR adds some additional guidance to encourage designers to consider the impact on the rest of the UI if the AI CTA disappears.

Does this MR meet the acceptance criteria?

• The MR title and commit messages meet the Pajamas commit conventions.
• The “What does this MR do?” section in the MR description is filled out, explaining the reasons for and scope of the proposed changes, per “Say why not just what”.
  • For example, if the MR is focused on usage guidelines, addressing accessibility challenges could be added in a separate MR.
• Relevant label(s) are applied to the MR.
• The MR is added to a milestone.
• If creating a new component page from scratch, it follows the page template structure.
• Content follows the Pajamas voice and tone guidelines, falling back on the GitLab Documentation Style Guide when needed.
• Related pages are cross-linked, where helpful. Component pages have related components and patterns defined in their Markdown front matter.
• If embedding a Figma file, it follows the Figma embed guide.
• Review requested from any GitLab designer or directly from a maintainer or trainee maintainer.
• Maintainer review follows the Pajamas UX maintainer review checklist.

Links