Remove expandable function

[alex-rogers-hub]

Pull request overview

Currently expandable section is very prominent and doesn't need to be expandable
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Pull request checklist

Please check if your PR fulfills the following:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Tests have been run locally and are passing (shinytest2::test_app())
• Code is styled according to tidyverse styling (checked locally with styler::style_dir() and lintr::lint_dir())

What is the current behaviour?

Expanding

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What is the new behaviour?

Non-expanding, more subtle

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Anything else

Addressing issue #83

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[rmbielby]

Some very minor changes to the example panel, but also please could you remove the underlying function itself from helper_functions.R.