RFR: JDK-8019361: [TESTBUG] Conflicting collector combinations in option list for GC tests

[Andrey Zakharov]

Hi, team
Here is very simple patch removing @ignore tag from test which was 
ignored due conflicting options which now has been checked by already 
added @required tag:

webrev:
http://cr.openjdk.java.net/~azakharov/8019361/webrev/

testbug:
https://bugs.openjdk.java.net/browse/JDK-8019361

Thanks.