RFR: 8331392: G1: Make HRPrinter distinguish between different types of reclamation

[Thomas Schatzl]

Hi all,

  while debugging some unrelated issues using the HRPrinter logging, I found it useful to discriminate between different sources of reclamation in the output. At least "cleanup" seems a bit non-descriptive to me, and only ever fit the case where we "cleaned up" completely empty regions during the Cleanup pause (pre jdk11).

Thanks,
  Thomas

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Commit messages:
 - 8331392

Changes: https://git.openjdk.org/jdk/pull/19013/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19013&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331392
  Stats: 18 lines in 4 files changed: 10 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/19013.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19013/head:pull/19013

PR: https://git.openjdk.org/jdk/pull/19013