RFR: 8367473: Shenandoah: Make the detailed evacuation metrics a runtime diagnostic option

[William Kemper]

Non-product builds currently have a feature to produce detailed metrics about evacuations (number of objects, number of bytes, split out by age (young, old, promotion) and thread (mutator or worker). This change makes this feature accessible in release builds as a diagnostic option.

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Commit messages:
 - Make detailed evacuation tracking a diagnostic option in product builds

Changes: https://git.openjdk.org/jdk/pull/27238/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27238&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8367473
  Stats: 36 lines in 4 files changed: 19 ins; 4 del; 13 mod
  Patch: https://git.openjdk.org/jdk/pull/27238.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27238/head:pull/27238

PR: https://git.openjdk.org/jdk/pull/27238