Update checkout support

[fditrapani]

Problem

In checkout, we have text that reads "Need extra help? Visit Help Center". In some cases, it opens the help center, in others, it opens a chat with a human. When you go to the help center, it's pretty open ended and doesn't feel helpful.

• Let's update it to simply say "Need help?"
• Let's open a new fresh chat

Where

• Purchase any product and go to checkout
• Try purchase 100-year domain: https://wordpress.com/100-year-domain/

[github-actions]

OpenAI suggested the following labels for this issue:

• [Feature Group] Checkout: The issue pertains directly to the checkout process and how support options are presented during that stage.
• [Feature] Customer Seller Experience: This relates to the user's experience while making a purchase and seeking assistance.
• [Feature] Help Center: The issue discusses the functionality related to the Help Center, specifically how help is accessed during checkout.

[fditrapani]

Related issue: #102003