RFR: Lower logging of collection set details to debug and use cset tag

[Kelvin Nilsen]

On Thu, 23 Mar 2023 22:43:39 GMT, William Kemper <wkemper at openjdk.org> wrote:

> This logging was unintentionally left at Info level.

This looks good.  (I did something similar when I merged this into my expand-on-demand.)

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Marked as reviewed by kdnilsen (Committer).

PR Review: https://git.openjdk.org/shenandoah/pull/232#pullrequestreview-1355771641