RFR: 8367450: Shenandoah: Log the composition of the collection set

[Paul Hohensee]

On Thu, 11 Sep 2025 21:40:50 GMT, William Kemper <wkemper at openjdk.org> wrote:

> Reuse the same log message from GenShen which details the composition of the live data to be evacuated. In the non-generational modes, all regions are considered young and nothing will be promoted (or old).

Shouldn't evacInfo be initialized via constructor?

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PR Review: https://git.openjdk.org/jdk/pull/27235#pullrequestreview-3226556674