RFR: 8371985: Parallel: Move should_attempt_scavenge to ParallelScavengeHeap

[Francesco Andreuzzi]

On Mon, 17 Nov 2025 09:49:30 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Move young/full-gc criteria heuristics outside of `psScavenge.cpp` so that young-gc API runs to completion.
> 
> Test: tier1-3

Marked as reviewed by fandreuzzi (Author).

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

PR Review: https://git.openjdk.org/jdk/pull/28346#pullrequestreview-3472073569