RFR: 8377513: jpackage: fix Win8365790Test test

[Alexey Semenyuk]

On Tue, 10 Feb 2026 00:41:41 GMT, Alexey Semenyuk <asemenyuk at openjdk.org> wrote:

> - Run the code in the worker thread using the same global variables as in the main thread. The NPE was caused by an attempt to access a global variable non-existing in the worker thread. This change prevents NPEs in the worker thread.
>  - Check for a thrown exception in the worker thread from the main thread to make the test fail if the worker thread fails.

@sashamatveev PTAL

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PR Comment: https://git.openjdk.org/jdk/pull/29642#issuecomment-3874951795