RFR: 8272364: Parallel GC adaptive size policy may shrink the heap below MinHeapSize [v5]

[Zhengyu Gu]

> This appears to be another miscalculation of gc ergonomics. When `NewSize` is not explicitly set, `MinNewSize` should be derived from `MinHeapSize` using `NewRatio`.
> 
> This pull request has dependency on [PR#18539](https://github.com/openjdk/jdk/pull/18539)

Zhengyu Gu has updated the pull request incrementally with one additional commit since the last revision:

  Reduce max heap size to 2GB in test, so it can run on 32-bit JVM

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Changes:
  - all: https://git.openjdk.org/jdk/pull/18877/files
  - new: https://git.openjdk.org/jdk/pull/18877/files/49449442..70c180fb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18877&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18877&range=03-04

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/18877.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18877/head:pull/18877

PR: https://git.openjdk.org/jdk/pull/18877