[lworld] RFR: Remove ensure_objArray and copying code and write a test

[Coleen Phillimore]

On Sun, 13 Jul 2025 22:21:19 GMT, Chen Liang <liach at openjdk.org> wrote:

> Note these two paths are only used by Constructor::newInstance and Method::invoke if system property -Djdk.reflect.useNativeAccessorOnly=true is set.

Yes, my test passes at property.

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PR Comment: https://git.openjdk.org/valhalla/pull/1507#issuecomment-3128147209