RFR: 8357801: Parallel: Remove deprecated PSVirtualSpace methods

[Thomas Schatzl]

On Mon, 26 May 2025 17:33:59 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple removing some deprecated methods by changing to pointer-type for some fields.
> 
> Test: tier1-3

Marked as reviewed by tschatzl (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/25459#pullrequestreview-2870576754