RFR: 8345040: Clean up unused variables and code in `generate_native_wrapper`

[Vladimir Kozlov]

On Tue, 26 Nov 2024 08:16:56 GMT, Qizheng Xing <qxing at openjdk.org> wrote:

> Some of variables and code are related to critical JNI natives feature, which was removed in JDK 18. This patch cleans them up.

Looks good to me.

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Marked as reviewed by kvn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22384#pullrequestreview-2462244909