config: add new child stops to harvard busway config

[sloanelybutsurely]

Summary of changes

The Harvard busway has been split into multiple child stops as of the 8/25/2024 rating. This adds those new child stops to the sources config of the Harvard upper busway sign.

Asana Ticket: (RTS) New child stops added to Harvard Busway for 8/25 rating start

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)
• signs.json changes were also made in signs_ui
  • config: add new child stops to harvard busway config signs_ui#1402
• 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)