<AWT Dev> RFR: 8254349: The TestNoScreenMenuBar test should be updated

[Sergey Bylokhov]

This test tries to run an external application to make itself non-active and then sets and checks the global menu.

But it has a few issues:
 - As an external app, the "System Settings" app is used, but it looks like in macOS Catalina this app was moved, and
   nothing actually starts
 - The external app is closed via osascript which required special permission, and it is requested via a modal dialog if
   not granted already
 - It looks like the attempt to close(already closed app, since the open step failed) the "System Settings" via osascript
   actually activates it instead

So to prevent one more permission, and usage of some external app I just use the same java test as an external app but
in a separate process. I have checked that the test fails if the fix for JDK-8146310 is removed.

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Commit messages:
 - Update TestNoScreenMenuBar.java

Changes: https://git.openjdk.java.net/jdk/pull/587/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=587&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254349
  Stats: 37 lines in 1 file changed: 18 ins; 5 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/587.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/587/head:pull/587

PR: https://git.openjdk.java.net/jdk/pull/587