RFR: 8361726: Shenandoah: More detailed evacuation instrumentation

Wed Jul 9 17:57:14 UTC 2025

Shenandoah has `product only` instrumentation to track evacuation performance. This change introduces more detail by categorizing each evacuation as young, old or promotion.

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Commit messages:
 - Convert evac tracking back into non-product feature
 - Re-enable evac tracker, account for young/old/promotions

Changes: https://git.openjdk.org/jdk/pull/26222/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26222&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361726
  Stats: 149 lines in 9 files changed: 79 ins; 26 del; 44 mod
  Patch: https://git.openjdk.org/jdk/pull/26222.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26222/head:pull/26222

PR: https://git.openjdk.org/jdk/pull/26222