RFR: 8315855: G1: Revise signature of set_humongous_candidate

[Albert Mingkun Yang]

Simple removing redundant method arg around humongous candidates.

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Commit messages:
 - g1-humongous-remset-true

Changes: https://git.openjdk.org/jdk/pull/15617/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15617&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315855
  Stats: 4 lines in 2 files changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/15617.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15617/head:pull/15617

PR: https://git.openjdk.org/jdk/pull/15617