Update help links on Marketing > Traffic page

[fditrapani]

Problem

The marketing traffic page has a few issues with the help links:

1. The Learn more link for Google analytics opens a support doc in a new window instead of opening the article in the help center.
   
2. The learn more link in the Sitemaps info tooltip opens a support guide in a new window instead of opening the article in the help center.
3. The "Site verification services" section has a "full instructions" link with a question mark icon. The link opens a support guide in a new window instead of opening the article in the help center. The icon isn't commonly used for links so we can drop that as well.

Let's make sure these updates make it to simple + atomic wp-admin as well as calypso screens.

Where

Visit Hosting > Marketing > Traffic in wp-admin.

[github-actions]

OpenAI suggested the following labels for this issue:

• [Feature Group] A8C Marketing & Sales: The issue is related to the marketing tools and processes, specifically the traffic page links.
• [Feature] Help Center: The issue addresses problems with help links, indicating a need for improvements in the Help Center's navigation.
• [Feature] Support Docs Content: The help links pointing to support documents suggest that the issue relates to updating the content available in support documentation.