Delete Svelte example

[JReinhold]

This PR deletes the Svelte example now that all the repros have been set up.

It turns out none of the stories in the Svelte example where not already covered by our default repro stories, so there was nothing to migrate, only delete. At least from what I could tell.

What I did

How to test

• Is this testable with Jest or Chromatic screenshots?
• Does this need a new example in the kitchen sink apps?
• Does this need an update to the documentation?

If your answer is yes to any of these, please make sure to include it in your PR.

[JReinhold]

@ndelangen @tmeasday I don't understand why the CI is failing here on the examples step. yarn build-storybooks --all exits 0 after 3 seconds, as if it couldn't find any examples and then it fails on persisting an empty dir.
But when I run it locally it builds plenty of Storybooks.

https://app.circleci.com/pipelines/github/storybookjs/storybook/30597/workflows/3e0f7273-d433-4092-bc3c-dd1024a0c506/jobs/429281

[tmeasday]

@JReinhold you just need to decrement the parallelism of the examples step. I'll do that for you!

[tmeasday]

LGTM