Simplify quote-to-cash page to focus on systems information.

Why is this change being made?

The quote to cash page is quickly becoming unruly and it has redundant parts with what belongs in the sub-team pages (e.g., team information such as who's part of Fulfillment belongs in https://about.gitlab.com/handbook/engineering/development/fulfillment/#team-members).

This MR focuses quote-to-cash page to focus on the systems designs and architecture, and remove the focus on who's on what team (link to the team pages instead as the SSOT) and removes mention of prioritization processes (each team has ownership over team prioritization).

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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