Apply devops::plan label to group::knowledge resources

What does this MR do and why?

Second step to Change Group to Knowledge Group for Issues with... (#1263 - closed), closes #1263 (closed).

I realized that gitlab-bot failed to apply the devopsplan label to resources labeled with groupknowledge after the migration ran in !2097 (closed). So creating this MR to make sure all resources labeled with groupknowledge has devopsplan label applied.

Expected impact & dry-runs

Before	After
groupknowledge without devopsplan	groupknowledge and devopsplan

Dry-run job: https://gitlab.com/gitlab-org/quality/triage-ops/-/jobs/3976766686

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