RFR: 8354310: JFR: Inconsistent metadata in ZPageAllocation

[Joel Sikström]

Hello,

This PR fixes JFR metadata for ZPageAllocation after [JDK-8350441](https://bugs.openjdk.org/browse/JDK-8350441).

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Commit messages:
 - 8354310: JFR: Inconsistent metadata in ZPageAllocation

Changes: https://git.openjdk.org/jdk/pull/24578/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24578&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354310
  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/24578.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24578/head:pull/24578

PR: https://git.openjdk.org/jdk/pull/24578