RFR: 8286624: Regression Test CoordinateTruncationBug.java fails on OL8.3

[Phil Race]

This was a closed test - simply because it hadn't been reviewed for moving to open
so I am doing it now whilst fixing a problem that was observed on the OL 8.x (and
by implication an RHEL 8.x) desktop due to the screen menu bar rendering over one
line of the undecorated window.
That was fixed by changing the location to use setLocationRelativeTo(null) vs
the previous implied (0,0)

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Commit messages:
 - 8286624

Changes: https://git.openjdk.org/jdk/pull/11120/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11120&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8286624
  Stats: 271 lines in 1 file changed: 271 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11120.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11120/head:pull/11120

PR: https://git.openjdk.org/jdk/pull/11120