Remove excess content and move information from landing page to its own dedicated pages for DCS

Why is this change being made?

As per the Digital Customer Success Programs epic (gitlab-com/sales-team/field-operations&313 (closed)), we want remove excess content in the Customer Programs handbook page and also move some old content to new dedicated pages where we can expand upon it as needed. In this MR I will:

• Remove excess/unneeded content
• Create an "Available Programs" page
• Create a "Getting Help from Digital Customer Success" page
• Add additional information and links to new pages, improve language clarity.

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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• 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
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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
  • 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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