RFR: 8252740: java/util/Properties/LoadAndStoreXMLWithDefaults.java fails after JDK-8252354

[jiefu(傅杰)]

Hi all,

JBS:    https://bugs.openjdk.java.net/browse/JDK-8252740
Webrev: http://cr.openjdk.java.net/~jiefu/8252740/webrev.00/

After JDK-8252354, properties whose keys or values are none strings won't be skipped any more.
Instead, ClassCastException will be thrown.

So this part of testing code is incorrect.
The fix just removes it.

Thanks.
Best regards,
Jie