Vue3: Fix support for onX and empty attributes in Show Code

[Tap-Kim]

Closes #25143

What I did

We have added code supplementation and test code to correct the issues below.

Describe the bug
In the "Show code" section, any prop containing "on" is rendered as a callback. The test should be whether the name starts with "on" rather than whether it contains "on".

To Reproduce
https://stackblitz.com/edit/github-j6h4hd?file=src%2Fstories%2FButton.vue,src%2Fstories%2FButton.stories.js&preset=node

Go to Button / Docs in the storybook
Click "Show code"
Edit the "icon" prop
-> The generated prop in "Show code" is icon="()=>({})" whatever the value you set.

Checklist for Contributors

Testing

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• stories
• unit tests
• integration tests
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• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

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[JReinhold]

Thanks for the contribution!

Checking for "on" with startsWith instead of includes makes sense to me, but I don't fully understand the part about removing empty functions/objects.

If you're passing in a function as an arg, why shouldn't that be shown in the documentation, even if it's an empty function?

[Tap-Kim]

@JReinhold
Hello! I'll take the test code as an example.

I was mistaken!
Changed to handle undefined and blank values, not empty function/object removal!

Thank you for your review :)