RFR: 8364531: G1: Factor out liveness tracing code

[Thomas Schatzl]

Hi all,

  please review this refactoring, eliminating some copy&paste, in cset candidate group liveness logging.

The output is mostly the same, except for the young cset group, where the "-" has been replaced to just print the default value (0.0) for efficiency. I did not see this important to have, the gc efficiency for young gen isn't interesting.

Testing: local compilation, gha, visual inspection of output

Thanks,
  Thomas

-------------

Commit messages:
 - 8364531

Changes: https://git.openjdk.org/jdk/pull/26591/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26591&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364531
  Stats: 60 lines in 2 files changed: 18 ins; 35 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/26591.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26591/head:pull/26591

PR: https://git.openjdk.org/jdk/pull/26591