[14] RFR 8240217: Shenandoah: remove ShenandoahEvacAssist

[Roman Kennke]

Looks good!

Thank you!
Roman


> Original RFE:
>   https://bugs.openjdk.java.net/browse/JDK-8240217
>   https://hg.openjdk.java.net/jdk/jdk/rev/c005ba590219
> 
> 14u fix does not apply cleanly due to context changes. This is not a big deal, because the conflict
> is in the hunk that removes the entire piece of code. 14u webrev:
>   https://cr.openjdk.java.net/~shade/8240217/webrev.14u.01/
> 
> Testing: hotspot_gc_shenandoah
>