Update Fulfillment categories

Why is this change being made?

As we've expanded the Fulfillment team, the categories of work have also increased. This MR updates our categories to better reflect the work that we are doing.

Draft list of categories and mapping to groups: https://docs.google.com/spreadsheets/d/13COp8h5f52BfWOLnv9Be7pzj_p0Pzo5CDdmStZfvYSU/edit#gid=1680992989

How to think about categories:

1. A group should have 1+ categories, but typically 1-3. Not too many categories per group.
2. Each category should be meaningful/meaty enough that you'd consider:
   1. Building a standalone Direction page for that category.
   2. Create a category labels within the GitLab product for it and use them to label issues.
   3. Consider doing maturity scores on the categories and invest in improving the category's maturity.
3. For product functionality/capabilities, categories are best if they map to how industry analysts think of categories. For Fulfillment, we should consider what's the closest proxy to that -- what are industry standard "chunks" of functionality?
4. A stage should have up to ~8 categories. Looking at our current list, we may consider splitting Fulfillment into two stages, though I don't yet have good naming/clustering for the stages (open to suggestions). For now, I've kept it as a single stage with ~12 categories.

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
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added.
• 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.

---