Resolve "Alerts should be responsive"

What does this MR do?

Centres alert text for smaller viewports

Are there points in the code the reviewer needs to double check?

Should we be overriding the .pull-right class or adding a new class with custom styles to the alert links parent element?

Why was this MR needed?

Alert text was becoming unformatted on medium viewports

Screenshots (if relevant)

Before: After: Mobile:

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 #25776 (closed)