[14] RFR (S) 8240948: Shenandoah: cleanup not-forwarded-objects paths after JDK-8240868

[Aleksey Shipilev]

Original RFE:
  https://bugs.openjdk.java.net/browse/JDK-8240948
  https://hg.openjdk.java.net/jdk/jdk/rev/61f6c19d1a56

The context is a bit different in 14.

14u webrev:
  https://cr.openjdk.java.net/~shade/8240948/webrev.14u.01/

Testing: hotspot_gc_shenandoah

-- 
Thanks,
-Aleksey