RFR: 8324553: Shenandoah: Move periodic tasks closer to their collaborators [v2]

[Aleksey Shipilev]

On Tue, 23 Jan 2024 23:45:36 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> This is a refactoring to move Shenandoah's periodic tasks from the control thread to their respective dependencies: the pacer and monitoring support. This change will facilitate reviews of the upcoming changes to isolate the generational mode changes.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Improve names and conformance to style guide

Looks fine.

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Marked as reviewed by shade (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17540#pullrequestreview-1842121428