Draft: Update workflows in prep for Reseller Customer access to Customers Portal

Why is this change being made?

Reseller customers will soon be able to access Customers Portal to view their subscriptions and self-provision access (SaaS and SM). For additional details about the new functionality, see Allow customers that purchased via Reseller to ... (gitlab-org&8941 - closed).

Related to Update Docs in prep for Reseller Customer acces... (gitlab-org/gitlab!117075 - merged)

⚠ This MR cannot merge until we are ready to go live with gitlab-org&8941 (closed).

Author Checklist

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/cc @gitlab-com/support/licensing-subscription

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