Fix style

Author: steve-s

graalpython/com.oracle.graal.python.test/src/com/oracle/graal/python/test/advance/LeakTest.java

@@ -40,15 +40,12 @@
  */
 package com.oracle.graal.python.test.advance;
 
-import java.io.BufferedWriter;
-import java.io.FileWriter;
 import java.io.IOException;
 import java.lang.management.ManagementFactory;
 import java.lang.management.ThreadInfo;
 import java.lang.management.ThreadMXBean;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;