fix: make viteMetadata property of RenderedChunk optional

[sapphi-red]

Description

viteMetadata property doesn't exist when a plugin is used with rollup. So the property should be optional.
refs #11511

https://github.com/vitejs/vite-ecosystem-ci/actions/runs/3964905502/jobs/6794171075#step:8:476

https://discord.com/channels/804011606160703521/1065932582946086953/1065932585924038706

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the PR Title Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[sapphi-red]

/ecosystem-ci run

[vite-ecosystem-ci]

📝 Ran ecosystem CI: Open

suite	result
astro	✅ success
histoire	❌ failure
iles	✅ success
ladle	✅ success
laravel	✅ success
marko	✅ success
nuxt-framework	✅ success
previewjs	❌ failure
qwik	❌ failure
rakkas	✅ success
sveltekit	❌ failure
vite-plugin-ssr	✅ success
vite-plugin-react	✅ success
vite-plugin-react-pages	❌ failure
vite-plugin-react-swc	✅ success
vite-plugin-svelte	✅ success
vite-plugin-vue	✅ success
vite-setup-catalogue	✅ success
vitepress	✅ success
vitest	✅ success
windicss	✅ success