29595 Customize experience callout design

What does this MR do?

Updates the design of the callout for customizing experience. Spacing is fixed and the callout looks more like a callout so it doesn't blend into the page so much. Dismiss icon is more visible.

Screenshots (if relevant)

Before:

After:

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #29595 (closed)