Ignore renovate bot from Community Contribution labeling

For security reasons we had to create a separate user which is not part of the gitlab-org & gitlab-com groups in order to run renovate. For more details see here 1.

Unfortunately this means that creating MRs with the user gitlab-renovate-bot now triggeres the thank you message for community contributions 2, which we do not want.

See also: triage-serverless!79 (merged)

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