RFR: 8331977: Crash: SIGSEGV in dlerror()

[Alexey Semenyuk]

Fix MainClassTest class to use HelloApp.AppOutputVerifier class to run app launcher instead of raw Executor. This makes MainClassTest test run app launchers with retries. This change addresses the primary issue.

Fix inconsistencies in HelloApp.AppOutputVerifier class. It used to provide API allowing to run launchers without retries. It inconsistently allowed the execution of launchers with suppressed output (stdout and stderr). It inconsistently executed launchers with/without PATH removed from the environment.

These loopholes were eliminated:

 - stdout and stderr of app launchers is never suppressed;
 - PATH env variable is always deleted for app launchers on Windows. It is not deleted on other platforms. This change sets the correct scope of [JDK-8254920](https://bugs.openjdk.org/browse/JDK-8254920) fix that introduced the removal of PATH env variable for app launchers;
 - app launchers are always executed with retries unless the launcher is executed with `jpackage.test.noexit` system property set to `true` indicating the test app will not terminate on its own.

Other changes are due to changes in HelloApp.AppOutputVerifier class.

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Commit messages:
 - Trailing spaces removed.
 - Run app launcher with retries if "jpackage.test.noexit" jpackage java option is not set or set to "false".  Otherwise run app launcher without retries. If the launcher never exits (jpackage.test.noexit=true), it should be terminated externally and thus it should not be restarted.
 - 8331977: Crash: SIGSEGV in dlerror()

Changes: https://git.openjdk.org/jdk/pull/19502/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19502&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331977
  Stats: 122 lines in 5 files changed: 48 ins; 41 del; 33 mod
  Patch: https://git.openjdk.org/jdk/pull/19502.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19502/head:pull/19502

PR: https://git.openjdk.org/jdk/pull/19502