test(e2e): revert all cases to CJS to fix timeout

[chenjiahan]

Summary

Since the merge of #4579, our E2E has started to timeout frequently.

After investigation, it appears that this is not related to the implementation of Rsbuild itself, but may be related to Playwright's transformation of ESM.

As it is difficult to locate the root cause, this PR reverts the previous changes to fix CI.

The minimal reproduction cases: pnpm run e2e:webpack cases/alias

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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