Update front matters of examples and outdated links

[alessioventuriniAND]

We need to update/remove the below values from the front matter of some examples to align them with the rest of the examples components.

• Remove layout: example from frontmatter of examples in DS
• Modify examples to specify layout: ~ instead of layout: none in DS

[alessioventuriniAND]

Once this ticket is completed and released we can then work on : https://github.com/orgs/ONSdigital/projects/21/views/1?pane=issue&itemId=11770046