Fix checkstyle failure

Author: abh1sar

server/src/test/java/org/apache/cloudstack/backup/BackupManagerTest.java

@@ -31,7 +31,6 @@
 import com.cloud.storage.dao.VolumeDao;
 import com.cloud.user.Account;
 import com.cloud.user.AccountManager;
-import com.cloud.user.AccountService;
 import com.cloud.user.AccountVO;
 import com.cloud.user.DomainManager;
 import com.cloud.user.ResourceLimitService;