Integrated: 8359868: Shenandoah: Free threshold heuristic does not use SoftMaxHeapSize

[William Kemper]

Clean backport. Has heuristics use soft max heap for free threshold tests.

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Commit messages:
 - Backport 974ad4e8cdddee7d932e8375258067f9d2ca6a8b

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/205/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah-jdk21u&pr=205&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359868
  Stats: 7 lines in 4 files changed: 0 ins; 3 del; 4 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/205.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/205/head:pull/205

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/205