RFR: Improved timing reports

[Kelvin Nilsen]

On Wed, 13 Apr 2022 17:33:28 GMT, William Kemper <wkemper at openjdk.org> wrote:

> This is a bundle of a few minor changes to the cycle and global timing reports:
> * Render coalescing phase closer to where it happens in the cycle
> * Include timing for remembered set swap and satb management during init mark pause
> * Emit a cycle report for old generation's bootstrap cycle
> * Track old GC cycles completed and interrupted for global report

Marked as reviewed by kdnilsen (Committer).

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PR: https://git.openjdk.java.net/shenandoah/pull/131