Most of failures were due to temporary test repos, users and/or teams
being left behind after the test run, and these left-over stuff in
$baseFolder/data/git caused assertion errors in many tests in subsequent
test runs. This fix tries to delete those left-over stuff at the end of
each test, mainly in their @Afterclass code blocks.

PushLogTest.java is deleted as it doesn't work, and has been superseded
with better tests in various protocol test suites (GitServletTest,
GitDaemonTest, SshDaemonTest, etc.)