Remove the userdemo section in examples

[Sigma-Verma]

PR summary

Closes #25800

To address this issue, the proposed fix is to convert the examples in the userdemo section from literalinclude to figure directives if they are still used in the documentation. This will allow the examples to be displayed as figures rather than code snippets
To address this issue, the proposed fix is to convert the examples in the userdemo section from literalinclude to figure directives if they are still used in the documentation. This will allow the examples to be displayed as figures rather than code snippets

PR checklist

• "closes #0000" is in the body of the PR description to link the related issue
• new and changed code is tested
• Plotting related features are demonstrated in an example
• New Features and API Changes are noted with a directive and release note
• Documentation complies with general and docstring guidelines

[QuLogic]

This appears to contain the changes from #25726 and should be rebased to be on top of the merged version.

[story645]

Given that this change would still require that the userdemo section exists, I'm wondering if @timhoffm meant that you should use the ..plot directive with the code inlined in the tutorial.