Disable USWDS default external link screen reader text

[aduth]

🛠 Summary of changes

Fixes an issue where external links doubly announce to screen readers that they open in a new window.

This addresses a few problems:

• Double announcement
• Lack of translation in non-English locales
• Confusing placement of the text before the link content

This should hopefully be a temporary patch, pending upstream improvements tracked at uswds/uswds#5942

📜 Testing Plan

1. Go to http://localhost:3000
2. Enable screen reader
3. Navigate to "Security Practices and Privacy Act Statement" link
4. Observe that the link only announces that it opens in a new tab a single time, in the page's current locale, and after the link's content is announced

👀 Screenshots

Language	Before	After
English
Chinese