RFR: 8344263: GenShen: Reduce extraneous log messages at INFO level [v7]

[Aleksey Shipilev]

On Wed, 20 Nov 2024 00:32:15 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Genshen logs a lot of fine level detail at `gc=info`. This category should be reserved for major phase changes in the gc cycle.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix old growth triggers test

Marked as reviewed by shade (Committer).

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PR Review: https://git.openjdk.org/shenandoah/pull/540#pullrequestreview-2448007688