RFR: 8360220: Deprecate and obsolete ParallelRefProcBalancingEnabled

[Thomas Schatzl]

On Mon, 23 Jun 2025 09:14:43 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Deprecating `ParallelRefProcBalancingEnabled`, which is used only by Parallel and G1, and both have it enabled by default.
> 
> Disabling it offers little benefit, so removing it do reduce the number commandline flags.

Marked as reviewed by tschatzl (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/25932#pullrequestreview-2949965234