RFR: 8236073: G1: Use SoftMaxHeapSize to guide GC heuristics [v2]

[Thomas Schatzl]

> Hi all,
> 
>   please review this change to implement `SoftMaxHeapSize` for G1.
> 
> Main change is that `SoftMaxHeapSize` now impacts the `G1IHOPControl::target_occupancy()`, i.e. the amount of bytes G1 when reclaim should start.
> 
> Most of the other changes are just about updating logging/JFR and making sure that the `SoftMaxHeapSize` values are consistent across calls.
> 
> Testing: tier1-5
> 
> Thanks,
>   Thomas

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  * actually add test

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/27524/files
  - new: https://git.openjdk.org/jdk/pull/27524/files/cc240b6a..ec1ccb7f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27524&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27524&range=00-01

  Stats: 138 lines in 2 files changed: 135 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27524.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27524/head:pull/27524

PR: https://git.openjdk.org/jdk/pull/27524