RFR: 8377513: jpackage: fix Win8365790Test test

[Alexey Semenyuk]

- 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.

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Commit messages:
 - Win8365790Test: fix test failure

Changes: https://git.openjdk.org/jdk/pull/29642/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29642&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377513
  Stats: 19 lines in 1 file changed: 11 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/29642.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29642/head:pull/29642

PR: https://git.openjdk.org/jdk/pull/29642