Draft: OLD - Reorganize data guide to xMAU analysis

Why is this change being made?

MR closed due to issues with rebasing. New MR: !124688 (merged)

The Data Guide to xMAU Analysis is dense and challenging to navigate for folks who have basic questions. This MR reorganizes the content to move the nitty gritty details to the end of the page. This will clear up the overview, yet retain the details for analysts or folks looking for bedtime reading.

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
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