RFR: 8328126: GenShen: Reduce verbosity of logging for satb mode

[Kelvin Nilsen]

Only dump collection-set details if Debug logging is enabled.  With this change, generational-mode and satb-mode logging will match in this regard.

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Commit messages:
 - Make satb-mode GC logging less verbose
 - Revert "Make satb-mode Info logging less verbose"
 - Make satb-mode Info logging less verbose
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Revert "Round LAB sizes down rather than up to force alignment"
 - Round LAB sizes down rather than up to force alignment
 - Revert "Remove dead code for inelastic plabs"
 - Remove dead code for inelastic plabs

Changes: https://git.openjdk.org/shenandoah/pull/405/files
  Webrev: https://webrevs.openjdk.org/?repo=shenandoah&pr=405&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328126
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah/pull/405.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/405/head:pull/405

PR: https://git.openjdk.org/shenandoah/pull/405