RFR: Minor test cleanup

[Erik Helin]

Hi all,

please review this small patch that properly cleans up a temporary directory from one test in `RepositoryTests` and also sets the `exceptionFormat` to `"full"` for all `test` targets (so that if a test fails we get full stacktraces).

Thanks,
Erik

## Testing
- `sh gradlew test` passes on Linux x64

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Commits:
 - 15085039: Minor test cleanup

Changes: https://git.openjdk.java.net/skara/pull/216/files
 Webrev: https://webrevs.openjdk.java.net/skara/216/webrev.00
  Stats: 2 lines in 2 files changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/216.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/216/head:pull/216

PR: https://git.openjdk.java.net/skara/pull/216