Refactor RepositoryTestCase to use LocalDiskRepository instead

org.eclipse.jgit.test/META-INF/MANIFEST.MF

org.eclipse.jgit.test/pom.xml

...t.test/tst/org/eclipse/jgit/lib/ConcurrentRepackTest.java

....jgit.test/tst/org/eclipse/jgit/lib/MockSystemReader.java

....jgit.test/tst/org/eclipse/jgit/lib/ReflogConfigTest.java

...it.test/tst/org/eclipse/jgit/lib/RepositoryCacheTest.java

...t.test/tst/org/eclipse/jgit/lib/RepositoryConfigTest.java

...git.test/tst/org/eclipse/jgit/lib/RepositoryTestCase.java

...lipse.jgit.test/tst/org/eclipse/jgit/lib/T0003_Basic.java

...it.test/tst/org/eclipse/jgit/revwalk/RevWalkTestCase.java

...test/tst/org/eclipse/jgit/transport/BundleWriterTest.java