chore: remove all legacy builder packages

[chenjiahan]

Summary

• Remove all legacy builder packages, as they are no longer used and we use Rsbuild now.
• move packages/builder/uni-builder to packages/cli/uni-builder as there are only one builder package.

Checklist

• I have added changeset via pnpm run change.
• I have updated the documentation.
• I have added tests to cover my changes.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 8233562

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