RFR: JDK-8247418: Only validate the certificates trust if using the default key user name.

[Andy Herrick]

Please review the small jpackage test fix at [1] to issue [2].

[1] http://cr.openjdk.java.net/~herrick/8247418/webrev.01/

[2] https://bugs.openjdk.java.net/browse/JDK-8247418

/Andy