[jdk21u-dev] RFR: 8347300: Don't exclude the "PATH" var from the environment when running app launchers in jpackage tests

[Goetz Lindenmaier]

I backport this to get the jpackage testing up-to-date. This simplifies further backports.

This change, [JDK-8347300](https://bugs.openjdk.org/browse/JDK-8347300), is included in the second commit.

To make it work, I backport  changes from https://bugs.openjdk.org/browse/JDK-8340311 "8340311: JPackage app-image exe launches multiple exe's in JDK 22+" as prerequisite.
Planned later backport 8365790 needs the adaptions of the test helper classes in 8340311, too.

**8340311 backport adaptions**

The 8340311 test helper changes patch almost cleanly to 21.
But I also need to take some changes to tests where the interface
to the helper classes changed.

Adaptions:

*    I had to modify the location of test/jdk/tools/jpackage/share/jdk/jpackage/tests/BasicTest.java which was moved by a later change already backported.
*    I resolved the copyright in LauncherAsServiceVerifier.java
 *   I omitted the changes to Win8301247Test.java. These mostly depend on previous, not backported changes and do not apply well.
*    Naturally I omitted the new tests in 8340311.

**8347300 backport adaptions**

To apply [JDK-8347300](https://bugs.openjdk.org/browse/JDK-8347300) for the second commit, I had to resolve several chunks because removePath was renamed to removePathEnvVar.

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Commit messages:
 - backport d69463e4bcbddd346b9486059c5ad3a1cb555632
 - Prereq: test improvements of 8340311

Changes: https://git.openjdk.org/jdk21u-dev/pull/2454/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2454&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347300
  Stats: 262 lines in 9 files changed: 190 ins; 15 del; 57 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2454.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2454/head:pull/2454

PR: https://git.openjdk.org/jdk21u-dev/pull/2454