chore: optimize the initialization of instance

[KarthusLorin]

Summary

• optimize the initialization of instance

Now, even if the instance is not undefined, it will still execute options.

Let options behind of ?? will improve performance.

Related issue (if exists)

Types of changes

• Docs change / Dependency upgrade
• Bug fix
• New feature / Improvement
• Refactoring
• Breaking change

Checklist

• I have added changeset via pnpm run changeset.
• I have added tests to cover my changes.

[changeset-bot]

🦋 Changeset detected

Latest commit: f2977f5

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

This PR includes changesets to release 16 packages

Name	Type
@rspack/core	Patch
@rspack/cli	Patch
@rspack/dev-middleware	Patch
@rspack/dev-server	Patch
@rspack/plugin-html	Patch
benchmarkcase-rspack-react-refresh	Patch
@rspack/postcss-loader	Patch
@rspack/dev-client	Patch
@rspack/plugin-minify	Patch
@rspack/plugin-node-polyfill	Patch
@rspack/binding-darwin-arm64	Patch
@rspack/binding-darwin-x64	Patch
@rspack/binding-linux-x64-gnu	Patch
@rspack/binding-win32-x64-msvc	Patch
@rspack/binding	Patch
@rspack/fs	Patch

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