Run app launchers in jpackage tests with retries on Linux only. Run them without retries on other platforms.
Supplementary remove `HelloApp.AppOutputVerifier.removePathEnvVar()` function. It sets an unused member field and is a leftover from [JDK-8347300](https://bugs.openjdk.org/browse/JDK-8347300) fix. This change has no functional impact; it cleans unused code. ------------- Commit messages: - 8333569: jpackage tests must run app launchers with retries on Linux only Changes: https://git.openjdk.org/jdk/pull/23454/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23454&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8333569 Stats: 42 lines in 3 files changed: 15 ins; 18 del; 9 mod Patch: https://git.openjdk.org/jdk/pull/23454.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/23454/head:pull/23454 PR: https://git.openjdk.org/jdk/pull/23454
