RFR: 8368501: Shenandoah: GC progress evaluation does not use generation

[Y. Srinivas Ramakrishna]

On Mon, 29 Sep 2025 21:24:58 GMT, William Kemper <wkemper at openjdk.org> wrote:

> Remove unused `generation` parameter from stop-the-world GC progress evaluation. Also, have `shMetrics` use the freeset for `usage`  details. This is a follow up to a comment from an unrelated PR: https://github.com/openjdk/jdk/pull/27456#issuecomment-3325724362.

Nice cleanup, thanks!

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Marked as reviewed by ysr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27561#pullrequestreview-3317009418