RFR: 8287558: Remove remset coarsening stats during g1 remset summary printing

[tqxia]

On Wed, 1 Jun 2022 12:43:38 GMT, tqxia <duke at openjdk.java.net> wrote:

> Remset summary printing prints coarsening statistics in addition to remset summaries; that information is either duplicated with "Coarsening (recent)" printouts (with gc+remset=debug) at GC start or all-zeros at GC end.
> 
> Given that Remset summary printing is enabled with gc+remset=trace which covers the recent/all coarsening statistics, the coarsening statistics during remset summary are somewhat duplicate (or useless for the after-gc one).
> 
> Remove the coarsening statistics from the remset summaries.

I think "Concurrent refinement threads times" and "Sampling task time" in "After GC RS summary" also have similar issues: they are all-zeros because the data does not get changed in the last GC cycle.

A possible way to fix this adding an additional flag to differentiate between "Before GC RS summary" and "After GC RS summary", I can include this fix in the current PR, if that is OK.

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PR: https://git.openjdk.java.net/jdk/pull/8971