RFR(XS): 8075658: Mark intermittently failuring core-svc tests

[Yekaterina Kantserova]

Hi,

Could I please have a review of this fix.

bug: https://bugs.openjdk.java.net/browse/JDK-8075658
webrev: http://cr.openjdk.java.net/~ykantser/8075658/webrev.00

Thanks,
Katja