Delete empty server-islands example

[delucis]

Changes

• Removes sever-islands/tsconfig.json in the examples directory.
• Looks like this example was removed in Remove some examples #12196 but create-astro updates #12083 accidentally reintroduced it by adding the tsconfig.json.
• Noticed this on https://astro.new/next/templates/ which links to this example, but has no content

Testing

• n/a

Docs

• n/a

[changeset-bot]

⚠️ No Changeset found

Latest commit: d290086

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