Better cleanup for jdk/test/java/io/File/createTempFile/SpecialTempFile.java

SpecialTempFile.java creates 'SpecialTempFile' in the default temp directory:

cat -n jdk/test/java/io/File/createTempFile/SpecialTempFile.java

    83 final String name = "SpecialTempFile";
    84 File f = new File(System.getProperty("java.io.tmpdir"), name);
    85 if (!f.exists()) {
    86 f.createNewFile();
    87 }

This file is not cleaned up later.

The preferred approach would be to create temporary test directories and files under the jtreg property user.dir instead, if it is defined.