Move feature-flag tracking issues to change management

Summary

When there is a development change that requires a feature flag https://docs.gitlab.com/ee/development/feature_flags/index.html#development-type a tracking issue is created using the feature flag rollout template https://gitlab.com/gitlab-org/gitlab/-/blob/master/.gitlab/issue_templates/Feature%20Flag%20Roll%20Out.md .

We discussed in production#7638 (closed) that the feature-flag rollout issue gitlab-org/gitaly#4421 (closed) didn't have much visibility outside the Gitaly team.

This issue is to discuss migrating feature-flag tracking issues to change management https://about.gitlab.com/handbook/engineering/infrastructure/change-management/ .

We might consider changing the existing /change declare or creating a new slash command /feature declare.

Related Incident(s)

Originating issue(s): gitlab-com/gl-infra/production#ISSUE_ID

Desired Outcome/Acceptance Criteria

Associated Services

Corrective Action Issue Checklist

  • Link the incident(s) this corrective action arose out of
  • Give context for what problem this corrective action is trying to prevent from re-occurring
  • Assign a severity label (this is the highest sev of related incidents, defaults to 'severity::4')
  • Assign a priority (this will default to 'Reliability::P4')