USWDS-Team: Remove label workflow from repos

[amyleadem]

Summary

Remove the YAML-based workflows that add the triage label to new issues. Identifying new items for triage is now being managed by this project board workflow instead. This project board workflow makes the triage label redundant.

Tasks

Remove the add-issue-labels.yml file from the following repos:

• uswds
• uswds-site
• uswds-compile
• uswds-sandbox
• public-sans

Note

We should consider replacing the add-to-project.yml files with an auto-add to project workflow in the project board. However, this workflow can only be added to a limited number of repos depending on account type. We should first figure out if we can add it to all of our repos.

[amyleadem]

Update

We merged this update in uswds-sandbox. I created a test issue in that repo and confirmed that it received the appropriate automations with no regressions. We should be good to move forward with this change in our other repos outlined in this issue. I'll move the other PRs into peer review.

cc: @dct2023