Updated list of stage groups that UXRs support

Why is this change being made?

Product teams were recently changed (through combining or renaming teams), so this MR was made to have an updated list of the teams UXRs support. This information was gathered from the UXR Allocation/Alignment sheet and the Product handbook page.

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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  • The when to get approval handbook section explains the workflow in more detail
• 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
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