RFR: 8311585: Add JRadioButtonMenuItem to bug8031573.java

[Harshitha Onkar]

On Sun, 27 Aug 2023 21:41:43 GMT, Rajat Mahajan <rmahajan at openjdk.org> wrote:

> I have made the test changes to include radio button in menu and tested the same and it works fine.

@rajamah Changes look good.

Minor nit: Remove unused imports

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PR Review: https://git.openjdk.org/jdk/pull/15441#pullrequestreview-1598867734