RFR: 8343226: Shenandoah: Move tenuring threshold constraint functions into shared constraints

[Roman Kennke]

On Tue, 29 Oct 2024 18:45:44 GMT, William Kemper <wkemper at openjdk.org> wrote:

> This change anticipates the [generational mode for Shenandoah](https://github.com/openjdk/jdk/pull/21273), which makes use of the `InitialTenuringThreshold` and `MaxTenuringThreshold` flags.

Looks good to me. Thanks!

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Marked as reviewed by rkennke (Lead).

PR Review: https://git.openjdk.org/shenandoah/pull/529#pullrequestreview-2408729533