RFR: 8234703: JFR TestOutOfProcessMigration.java should clean up files

[Erik Gahlin]

Hi,

Could I have review of a fix that makes sure test files are cleaned up 
properly before the test exits.I also removed meaningless printing of 
the object identify of OutputAnalyzer.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8234703

Webrev:
http://cr.openjdk.java.net/~egahlin/8234703/

Testing: /jdk/jdk/jfr/ multiple times.

Thanks
Erik