Draft: Relabel CI variables resources to pipeline authoring

What is this label migration for?

Re: #1557 (closed)

Expected impact & dry-runs

Link to the last successful dry-run for reviewer to validate this label migration.

Action items

• Ensure you have read the label migration documentation
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Engineering week-in-review
• Close the MR (Don't Merge!) after migration is done.