RFR: Clean up Shenandoah configurations in shared tests

[Aleksey Shipilev]

On 10/11/2018 08:15 PM, Roman Kennke wrote:
> What would happen if one tried to run a test that has
> -XX:+UseShenandoahGC (e.g. next to UseCMS) in a build without
> Shenandoah? Is there a way to predicate tests to only run in this config
> if the config is actually present?

That would probably fail. We would need to test for that specially (later).

-Aleksey