RFR: 8273909: vmTestbase/nsk/jdi/Event/request/request001 can still fail with "ERROR: new event is not ThreadStartEvent"

[Alex Menkov]

The changes fixes discovered issues with getEventSetForThreadStartDeath method and its callers:
- getEventSetForThreadStartDeath must resume suspended thread(s), otherwise it can never get desired event;
- callers should not call addCountFilter;
also simplifies getEventSetForThreadStartDeath.

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Commit messages:
 - Fixed getEventSetForThreadStartDeath and its callers

Changes: https://git.openjdk.java.net/jdk/pull/5567/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5567&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273909
  Stats: 23 lines in 4 files changed: 7 ins; 12 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5567.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5567/head:pull/5567

PR: https://git.openjdk.java.net/jdk/pull/5567