RFR: Disable aggressive+verification test configs

[Aleksey Shipilev]

Testing on some machines revealed that the aggressive+verification combo drops
down the mutator utilization so much the tests are not progressing quickly
enough, and timeout.

The intermediate solution is to disable that combo:
  http://cr.openjdk.java.net/~shade/shenandoah/tests-no-aggressive-verify/webrev.01/

Testing: hotspot_gc_shenandoah

Thanks,
-Aleksey