RFR: 2082: Use correct .jcheck/conf in AdditionalConfiguration.java [v3]

[Erik Duveblad]

> Hi all,
> 
> please review this patch that ensures that we pass the correct `.jcheck/conf` to [AdditionalConfiguration.java](https://github.com/openjdk/skara/blob/master/bots/pr/src/main/java/org/openjdk/skara/bots/pr/AdditionalConfiguration.java). The `.jcheck/conf` should either come from the "overriding" `.jcheck/conf` (if the PR bot is configured to use that) or the pull request's target branch.
> 
> I have added that test that passes with this patch but fails without it.
> 
> Thanks,
> Erik

Erik Duveblad has updated the pull request incrementally with one additional commit since the last revision:

  optimize

-------------

Changes:
  - all: https://git.openjdk.org/skara/pull/1578/files
  - new: https://git.openjdk.org/skara/pull/1578/files/9a677529..ef47a259

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1578&range=02
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1578&range=01-02

  Stats: 5 lines in 1 file changed: 4 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/skara/pull/1578.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1578/head:pull/1578

PR: https://git.openjdk.org/skara/pull/1578