Draft: Apply ~"Support Team Contributions" automatically

What does this MR do and why?

We track contributions from the Support Team using the Support Team Contributions label, but it's easy to forget adding it. Considering that we can easily determine if someone is a Support Team member, adding this label can and should be automated.

Expected impact & dry-runs

• dry-run job: https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/3737067962
• I'm not sure why it didn't actually perform the actions – I assumed that when using the playground project it would actually perform the actions even with the dry-run job.
• Both test cases seem to work as expected, though:
  • MR by me (Support Team member): https://gitlab.com/gitlab-org/quality/engineering-productivity/triage-ops-playground/-/merge_requests/5
  • MR by a colleague (not a Support Team member): https://gitlab.com/gitlab-org/quality/engineering-productivity/triage-ops-playground/-/merge_requests/6
  • Only my MR would have gotten the label added, as expected.

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