private void deleteBackupDirectoryIfExist() throws Exception {
    if (Files.exists(accountBackupDir)) {
      Files.walk(accountBackupDir).map(Path::toFile).forEach(File::delete);
      Files.deleteIfExists(accountBackupDir);
    }
  }
Delete backup directory if exist.
@throws Exception Any unexpected exception.
ambry-account/src/test/java/com/github/ambry/account/HelixAccountServiceTest.java