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

[Rui Li]

Shenandoah some of the usages of [ShenandoahMinFreeThreshold](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp#L193) and [ShenandoahCriticalFreeThreshold](https://github.com/openjdk/jdk/blob/ba0c12231b0f5b680951e75765b5d292f31a2cbc/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp#L445) use max capacity instead of [soft max capacity](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/gc/shared/gc_globals.hpp#L528). 

This change replaces those usages with soft max heap size values.

tier1 tests are in progress

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Commit messages:
 - Fix after 8358529
 - 8359868: Shenandoah: Free threshold heuristic does not use SoftMaxHeapSize

Changes: https://git.openjdk.org/jdk/pull/26199/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26199&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/jdk/pull/26199.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26199/head:pull/26199

PR: https://git.openjdk.org/jdk/pull/26199