Update Fulfillment Sub-department Vision

Why is this change being made?

This MR is part of Restructure Fulfillment Handbook Pages https://gitlab.com/gitlab-org/fulfillment-meta/-/issues/321

This MR shortens the Fulfillment Sub-department Vision into 1-2 concise sentences.

It is modelled after the

(1) Vision for the Development Department https://about.gitlab.com/handbook/engineering/development/

A world class development team of software engineers and managers who make our customers happy when using our product(s). Our products should contain broad rich features, high availaiblity, high quality, fast performance, trustworthy security, and reliable operation.

(2) Vision for the Enablement Department https://about.gitlab.com/handbook/engineering/development/enablement/

Offer enterprise-grade operational experience of GitLab products from streamlined deployment and maintenance, disaster recovery, secure search and discoverability, to high availability, scalability, and performance.

Author Checklist

• Provided a concise title for the 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 change to the correct DRI(s)
  • 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 in on the page being edited.
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• 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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