Catch Contractor contributions earlier

What does this MR do and why?

Stop labelling Contractor Contribution as Community contribution

Example MR: gitlab-org/gitlab!150297 (closed)

This pollutes our community stats and makes it harder to see the real Community contribution

In this case, the schedule that catches Contractor Contribution will eventually get there, but this clumsily adds additional noise to the MR.

Expected impact & dry-runs

https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/6687299606 (correctly)

Didn't catch the abovementioned MR, after the wrong labels had been removed from the MR

See https://gitlab.com/gitlab-org/quality/triage-ops/-/tree/master/doc/scheduled#testing-policies-with-a-dry-run on how to perform dry-runs for new policies.

See https://gitlab.com/gitlab-org/quality/triage-ops/-/blob/master/doc/reactive/best_practices.md#use-the-sandbox-to-test-new-processors on how to make sure a new processor can be tested.

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