RFR: 8360206: Refactor ReferenceProcessor::balance_queues

[Thomas Schatzl]

On Mon, 23 Jun 2025 08:30:26 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple refactoring to clean up the inner-loop conditions and control flow. Due to the structural change, the diff is slightly large and may be harder to read than the resulting code. The new version simplifies the logic by using a single `remaining_to_move` counter in the inner loop to track remaining work, and introduces early returns to reduce indentation and improve clarity.
> 
> Test: tier1-3

lgtm.

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Marked as reviewed by tschatzl (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25930#pullrequestreview-2949956670