Add manager_approved and eoc_approved to C1 and C2 criticalities

Why is this change being made?

C1 and C2 Change criticalities requires both Management Approval and EOC approval. The current process is unclear in which format the Management Approval should be given. This approval is usually given via a comment or applying the manager_approved label. The EOC process is different and requires written approval on both Slack and the issue.

This MR provides a more unified way of approving both Management and EOC. It makes the process more prescriptive, explicitly stating the requirement of having the manager_approved label and the eoc_approved label on the Change Request issue to provide the approvals while preserving the log trail requirement needed for compliance reasons.

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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• Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies
• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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