RFR: 8318713: G1: Use more accurate age in predict_eden_copy_time_ms

[Albert Mingkun Yang]

One line fix in max-age used in predicting the num of surviving bytes.

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Commit messages:
 - g1-eden-count

Changes: https://git.openjdk.org/jdk/pull/16344/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16344&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318713
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16344.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16344/head:pull/16344

PR: https://git.openjdk.org/jdk/pull/16344