RFR: 8359701: G1: Move heap expansion time tracking of G1CollectedHeap:expand to call site

[Albert Mingkun Yang]

Simple patch of moving time-tracking logic from callee to caller, which removes a default arg. The default-arg is there because there are other callers that don't use/need this time-tracking logic.

Test: tier1

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Commit messages:
 - g1-expand-time

Changes: https://git.openjdk.org/jdk/pull/25835/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25835&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359701
  Stats: 12 lines in 2 files changed: 1 ins; 6 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/25835.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25835/head:pull/25835

PR: https://git.openjdk.org/jdk/pull/25835