RFR: 8347300: Don't exclude the "PATH" var from the environment when running app launchers in jpackage tests [v2]

[Alexey Semenyuk]

> - Don't remove the `PATH` variable from the environment when running app launchers in jpackage tests;
> - Fix tests that use `Executor` rather than `HelloApp` class to run app launchers: apply the same changes to the environment as would be applied by `HelloApp` class.
> - Replace `Executor.setRemovePathEnvVar()` with `Executor.removeEnvVar()` to support removal of any variable from the environment of a child process executed in jpackage tests;
> - Add support of a new boolean property `jpackage.test.clear-app-launcher-java-env-vars` in jpackage tests. If it is set to "true", the `JAVA_TOOL_OPTIONS` and `_JAVA_OPTIONS` variables will be removed from the environment of app launchers executed in jpackage tests. It is handy in local testing using jpackage test runner instead of the jtreg.
> 
> The first and the second changes are unrelated to other changes. They are bundled together as they apply to the same source code.

Alexey Semenyuk has updated the pull request incrementally with one additional commit since the last revision:

  Fix copyright year

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Changes:
  - all: https://git.openjdk.org/jdk/pull/22983/files
  - new: https://git.openjdk.org/jdk/pull/22983/files/dce50596..a865317a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22983&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22983&range=00-01

  Stats: 4 lines in 4 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/22983.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22983/head:pull/22983

PR: https://git.openjdk.org/jdk/pull/22983