Fix MainTest.java to ignore optional environment-specific errors in jpackage's output
------------- Commit messages: - 8372385: tools/jpackage/junit/share/jdk.jpackage/jdk/jpackage/internal/cli/MainTest.java fails Changes: https://git.openjdk.org/jdk/pull/28519/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28519&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8372385 Stats: 59 lines in 1 file changed: 53 ins; 0 del; 6 mod Patch: https://git.openjdk.org/jdk/pull/28519.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/28519/head:pull/28519 PR: https://git.openjdk.org/jdk/pull/28519
