fix(optimizer): only run require-import conversion if require'd

[sapphi-red]

Description

#8459 introduced external require-import conversion but it was applied not only to CJS.
It made reload by "newly found deps" happening frequently.

This PR makes the conversion only applied to CJS.
#8459's test covers this change.

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 Commit 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.

[netlify]

✅ Deploy Preview for vite-docs-main ready!

Name	Link
🔨 Latest commit	e8f8d30
🔍 Latest deploy log	https://app.netlify.com/sites/vite-docs-main/deploys/62b836f77628540008b84cb6
😎 Deploy Preview	https://deploy-preview-8795--vite-docs-main.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.