RFR: JDK-8328303: 3 JDI tests timed out with UT enabled [v2]

[Alex Menkov]

> The change fixes 3 nsk JDI tests.
> Root cause in all 3 tests is the same - the tests requests JDI event with SUSPEND_ALL policy, but event handler thread stops handle incoming event and this causes debuggee to hang (suspended by JDI event).
> 
> All 3 tests are updated to exit event handler thread after getting VMDeathEvent or VMDisconnectEvent (and resume debuggee after any other events).
> ClassPrepareEvent tests need to wait some time to allow handle all expected events before terminate the debuggee. The logic was implemented by using CountDownLatch.
> 
> All tests are passed with "--test-repeat 20"

Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:

  feedback

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18442/files
  - new: https://git.openjdk.org/jdk/pull/18442/files/cdcb4094..a30e3b70

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18442&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18442&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/18442.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18442/head:pull/18442

PR: https://git.openjdk.org/jdk/pull/18442