RFR: 8325616: JFR ZGC Allocation Stall events should record stack traces

[Stefan Karlsson]

We currently don't record the stack traces when sending the JFR ZGC Allocation Stall events. Let's add stack traces to the the jdk.ZAllocationStall event.

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Commit messages:
 - 8325616: JFR ZGC Allocation Stall events should record stack traces

Changes: https://git.openjdk.org/jdk/pull/17803/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17803&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8325616
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/17803.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17803/head:pull/17803

PR: https://git.openjdk.org/jdk/pull/17803