chore(ia): clean up health check wizard

[miguelpeixe]

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

The Health Check wizard has been deprecated.

How to test the changes in this Pull Request:

There shouldn't be any functional change, as the Health Check wizard is already invisible in the new UI. Navigate the "Newspack -> Dashboard" and "Newspack -> Settings" pages and tabs and confirm there are no errors.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[dkoo]

No problems that I can see! Maybe we should amend the docblock for this method too? These are plugins that have been tested with our platform in production, but for which we don't provide any direct support.