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

[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"

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Commit messages:
 - fix

Changes: https://git.openjdk.org/jdk/pull/18442/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18442&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328303
  Stats: 93 lines in 3 files changed: 32 ins; 22 del; 39 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