Scheduled automation to label duplicate incidents root cause

What does this MR do and why?

Closes Scheduled automation to label duplicated master... (#1505 - closed)

This is a scheduled automation to apply the root cause label if it was closed as a duplicate

Expected impact & dry-runs

https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/6769023399

Action items

• If adding environment variables for reactive processors, update config/triage-web.yaml and .gitlab/ci/triage-web.yml
• (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 =>
  • Engineering week-in-review