RFR: Remove dead-weight ShenandoahPrinter

[Roman Kennke]

Yep.

> Long time ago, we have move printing routines to ShenandoahPrinter on the off chance someone would
> need them. Apparently, nobody does need them. Let's purge those files from the repo:
> 
> $ hg qdiff | diffstat
>  shenandoahPrinter.cpp |  107 --------------------------------------------------
>  shenandoahPrinter.hpp |   51 -----------------------
>  2 files changed, 158 deletions(-)
> 
> Testing: tier1_gc_shenandoah
> 
> Thanks,
> -Aleksey
>