RFR (S) 8242625: Shenandoah: restore heap logging for Degenerated/Full cycles

[Roman Kennke]

Ok.

Thanks,
Roman

> Bug:
>   https://bugs.openjdk.java.net/browse/JDK-8242625
> 
> This is another logging regression since JDK-8241984. Fix is similar to what JDK-8242400 done:
>   https://hg.openjdk.java.net/jdk/jdk/rev/7992ff451fec
> 
> Webrev:
>   https://cr.openjdk.java.net/~shade/8242625/webrev.01/
> 
> Testing: eyeballing gc logs, hotspot_gc_shenandoah (running)
>