RFR: 8255031 : Update java/util/prefs/AddNodeChangeListener.java to report more failure info

[Brent Christian]

Hi,

The java/util/prefs/AddNodeChangeListener.java test fails once in a while in the automated test system.  Previous
failures were traced to machine configuration errors, but that does not appear to be the case this time.

My efforts to reproduce this failure have been unsuccessful.  The only useful infformation I've gleaned so far from the
test failure logs is that the overall duration for running tier1 is longer than usual when the test failure happens.

I would like to make the following updates to the test, in hopes of learning more if and when this test fails again:

* fail faster, to report if it is addNode() or removeNode() that is failing
* make multiple attempts to sleep+check the NodeChangeListener.  (If the test fails after a single sleep, but passes
  after waiting longer, maybe we just need to sleep for longer to account for the occasional slower tier1 test run).
* a few indentations fixes

Thanks,
-Brent

-------------

Commit messages:
 - remove trailing spaces
 - update test: fail eariler, repeat sleep+check

Changes: https://git.openjdk.java.net/jdk/pull/773/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=773&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255031
  Stats: 52 lines in 1 file changed: 33 ins; 3 del; 16 mod
  Patch: https://git.openjdk.java.net/jdk/pull/773.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/773/head:pull/773

PR: https://git.openjdk.java.net/jdk/pull/773