RFR: 1478: Add metrics and loggin measuring time before WorkItems start to run [v3]

[Magnus Ihse Bursie]

On Wed, 15 Jun 2022 11:19:02 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

>> In order to investigate and assess performance issues with the Skara bots, I need more data. One key class of data I'm missing is the time it takes from when a WorkItem is created or submitted to when it actually starts to run. This patch adds both metric gauges and log messages that include this information.
>
> Erik Joelsson has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - Merge branch 'master' into SKARA-1478-pending-metrics
>  - Fix divider
>  - Added comment
>  - SKARA-1478

Looks fine.

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Marked as reviewed by ihse (Reviewer).

PR: https://git.openjdk.org/skara/pull/1337