RFR: 8196750 [Testbug] tools/launcher tests need to tolerate unrelated warnings

[Andrey Nazarov]

Hi,

Please review fix in launcher tests.

Review: http://cr.openjdk.java.net/~anazarov/JDK-8196750/webrev/
Bug: https://bugs.openjdk.java.net/browse/JDK-8196750?filter=-1

—Thanks,
 Andrei