cleaning up the change-management page and adding change scoped lables

Why is this change being made?

To address questions raised in https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/8516. Please see the issue for details.

Related MR: gitlab-com/gl-infra/production!11 (merged)

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what