RFR: 1734: Reduce disk usage in pr bot [v2]

[Erik Joelsson]

On Thu, 27 Apr 2023 23:38:38 GMT, Zhao Song <zsong at openjdk.org> wrote:

>> As Erik mentioned in the issue, currently, pr bot would create multiple repository clones in different sub directory in the scratch directory which resulting in significant disk space wastage within the container. 
>> 
>> In this patch, the repository clones will be stored in a single directory at `scratch-x/pr/repos/repoName`, allowing different types of `WorkItems` to reuse this space.
>
> Zhao Song 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 six additional commits since the last revision:
> 
>  - fix import
>  - fix import
>  - Merge branch 'master' into SKARA-1734
>    
>    # Conflicts:
>    #	bots/pr/src/main/java/org/openjdk/skara/bots/pr/CSRCommand.java
>  - add some comments
>  - introduce ScratchArea
>  - SKARA-1734

Marked as reviewed by erikj (Lead).

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PR Review: https://git.openjdk.org/skara/pull/1491#pullrequestreview-1405978179