Replace "taskkill" and powershell script managing child processes started by jpackage tests on Windows with `java.lang.Process` API.
------------- Commit messages: - Simplify process termination on Windows. Changes: https://git.openjdk.org/jdk/pull/29172/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29172&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8375050 Stats: 238 lines in 8 files changed: 67 ins; 126 del; 45 mod Patch: https://git.openjdk.org/jdk/pull/29172.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/29172/head:pull/29172 PR: https://git.openjdk.org/jdk/pull/29172
