WIP: Cleaning up skeleton or placeholder content

What does this MR do?

This is a discussion regarding "Keep it simple" ways to do work using skeletons, placeholders and in other ways.

Some questions came up while reviewing this merge request !18266 (merged)
It uses the skeleton based documentation approach which is one way to keep it small, and proceed with small MRs. Based on the frontend development process we could put here in the description:

Skeleton based plan Start with an MR that has the skeleton of the components with placeholder content. In following MRs you can fill the components with interactivity. This also makes it easier to spread out development on multiple people.

Questions I'm trying to answer:

1. Is it ok to allow skeleton code with empty states and with placeholder texts (such as "Placeholder text") into the master and release in the production?
2. How long and in which state (behind a feature flag or otherwise) this code should remain in the live repository and in production
3. How to ensure a cleanup if the "skeleton-based" or "keep it simple" approach is aborted

Screenshots

N/A

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• [-] Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Performance and Testing

• [-] Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team