Update text for Union Square Shuttles to replace 86 with 109

[robbie-sundstrom]

Summary of changes

Asana Ticket: Update text for union square shuttles

Route 86 will no longer service Union Square after the Bus Network Redesign, and be replaced at Union Square by Route 109.

Reviewer Checklist

• Meets ticket's acceptance criteria
• Any new or changed functions have typespecs
• Tests were added for any new functionality (don't just rely on Codecov)
• If signs.json was changed, there is a follow-up PR to signs_ui to update its dependency on this project
• This branch was deployed to the staging environment and is currently running with no unexpected increase in warnings, and no errors or crashes (compare on Splunk: staging vs. prod)

[digitalcora]

First PR! 🎊

[digitalcora]

1️⃣0️⃣9️⃣✅

Brett may have gone over this with you already, but we generally avoid merge commits. So either "Squash and merge" (probably most convenient for this specific change), or rewrite commits to how you want them to look on main and then "Rebase and merge".

[panentheos]

Looks great! Just calling out that we're going to hold off on merging/deploying this, so we can time it for when the new route takes effect.