fix: prevent migrated snippet from shadow snippet prop

[paoloricciuti]

Closes #14090

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[changeset-bot]

🦋 Changeset detected

Latest commit: 06593a0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

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svelte	Patch

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[pkg-pr-new]

pnpm add https://pkg.pr.new/svelte@14127

commit: 06593a0