Remove dependencies on codeblock linenumbers and line highlighting.

[jhkrug]

To investigate and remove the use of code block line numbering and code block line highlighting.

Why?

Asciidoc/Antora, for product documentation, has a simple, lean highlighting package. No line numbering or line highlighting.

These features are used in Docusaurus, for community documentation.

If the use of these features can be removed from use in Docusaurus/community then transfer to AD/Antora, and maintenance is simplified.

[jhkrug]

First proposal is in #469.

[jhkrug]

Fixed by #469