RFR: 8345148: Fix for JDK-8337317 is incomplete

[Alex Menkov]

Fix for JDK-8337317 (#20699) updated serviceability/jvmti/HiddenClass and serviceability/jvmti/VMObjectAlloc tests adding guards against JVMTI_ERROR_WRONG_PHASE errors, but missed to enable JVMTI_EVENT_VM_DEATH events.
This fix adds the missed part.

Testing: hotspot/jtreg/serviceability/jvmti on all platforms
Manually verified test outputs contain "VMDeath" notification from VMDeath callback

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Commit messages:
 - fix

Changes: https://git.openjdk.org/jdk/pull/22426/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22426&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8345148
  Stats: 12 lines in 2 files changed: 10 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/22426.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22426/head:pull/22426

PR: https://git.openjdk.org/jdk/pull/22426