Remove the sell fllow

[autumnfjeld]

See parent issue.

This task will remove the sell flow.

[github-actions[bot]]

OpenAI suggested the following labels for this issue:

• [Feature Group] Customer Seller Experience: The title 'Remove the sell flow' suggests a focus on the experience users have when selling, which fits under customer seller experience.
• [Feature] Checkout: Removing a selling feature likely relates to the checkout process for purchases made on the platform.
• [Feature] Purchase Management: Changes to selling functionalities will impact how purchases are managed, which is pertinent for understanding user engagements with billing.
• [Feature] WPCOM Store & Purchases: Since the issue pertains to selling and possibly involves the store aspect on WordPress.com, this label is relevant.