Stop referencing the removed "facet labels" section

The section "Facet labels" has been removed in gitlab-org/gitlab!46271 (merged)

I've noticed it while completing my first Community triage issue ❤

Action items

• (If applicable) Add documentation to the handbook pages for Triage Operations =>
• (If applicable) Identify the affected groups and how to communicate to them:
  • /cc @person_or_group =>
  • Relevant Slack channels =>
  • Week-in-review