Adding engineering metrics process with stages/group label changes

We need to ensure that engineering dashboards and automating triage mechanisms are updated to reflect stage/group label changes.

• For every label change, please loop in the Dir of Quality to reroute to Engineering Productivity team.
• Please create a "Label change" issue in the project https://gitlab.com/gitlab-org/quality/triage-ops. with the template: https://gitlab.com/gitlab-org/quality/triage-ops/blob/master/.gitlab/issue_templates/label-change.md

For large changes, we need a roll-out plan to ensure that metrics for each development department sections are reflecting correctly. gitlab-org/quality/triage-ops#172 (closed) This is to avoid data loss similar to gitlab-org/gitlab-insights#113

@jeremy @joshlambert I would like your eyes on this first before I open to all of @gl-product.

@rymai @markglenfletcher @godfat for FYI.