Update customer collaboration project use cases in handbook

Why is this change being made?

Clarify use-cases for issues created within the Customer Collaboration Project to ensure that Support-specific queries are submitted as tickets in Zendesk, enabling Support to action customer queries efficiently.

Updated proposal suggests removal of the following items from the handbook page:

- List of [Members in the Zendesk Support](https://about.gitlab.com/support/managing-support-contacts/#managing-contacts) [Shared Organization](https://about.gitlab.com/support/managing-support-contacts/#shared-organizations) maintained by the customer with full history for governance (git history).
- [Interacting with the Product Team](/handbook/customer-success/csm/product/#product-interacting-with-csms) and [Prioritizing Customer issues](/handbook/product/product-processes/customer-issues-prioritization-framework/#customer-success).
- [Public Pages for Issue creation](https://gitlab.com/gitlab-com/account-management/templates/customer-collaboration-project-template/-/tree/master/public).
- [ServiceDesk Function](https://docs.gitlab.com/ee/user/project/service_desk/), to enable other users of the customer without a role in the Customer Collaboration Project to create issues. The CSM should notify the customer that the Collaboration Project is not meant for product support and troubleshooting inquiries.

Moved original Labels proposal to a project-specific README update here.

Click to expand original proposal including labels

We've been discussing the use of the Customer Collaboration project for a customer. I've created some labels for review and I want to discuss modification or omission from the handbook of some of the Support-specific tasks that seem to be represented in the Use cases for the Customer Collaboration Projects reference.

Proposing the use of the following labels: https://gitlab.com/groups/gitlab-com/account-management/-/labels?subscribed=&search=customer-collab

Label	Description
customer-collab special-projects	Special projects (Proof of Value, Value stream assessment, different Subscription at the customer) or an Group access token - API key for automations.
customer-collab enablement	Async Planning of Enablement Sessions.
customer-collab reference-architecture	Architecture diagram with history (git history).
customer-collab retrospective	Async retrospectives, with retrospective issue creation.
customer-collab service-usage	Sharing service ping metrics, graphics, and Usage metrics guides via PDF, CSV with GitLab from the Customer.
customer-collab solution-architect	SA (Solution Architect) activities tracked for example demos or POVs.
customer-collab support-zd-contacts	List of Members in the Zendesk Support Shared Organization maintained by the customer with full history for governance (git history).

Author and Reviewer Checklist

Please verify the check list and ensure to tick them off before the MR is merged.

• Provided a concise title for this Merge Request (MR)
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