RFR(T): 8223427: [TESTBUG] Disable JTReg Shenandoah tests when Graal is enabled

[Pengfei Li (Arm Technology China)]

Thanks Aleksey. Is it required to have another reviewer for this change?

--
Thanks,
Pengfei

> > Could anyone help review this patch (tiny change on 75 test files)?
> >
> > Webrev: http://cr.openjdk.java.net/~pli/rfr/8223427/webrev.00/
> > JBS: https://bugs.openjdk.java.net/browse/JDK-8223427
> 
> Looks good.
> 
> We already have a few tests that do "@requires vm.gc.Shenandoah
> & !vm.graal.enabled".
> 
> -Aleksey