RFR (S) 8230024: Shenandoah: remove unnecessary ShenandoahTimingConverter

[Aleksey Shipilev]

RFE:
  https://bugs.openjdk.java.net/browse/JDK-8230024

Webrev:
  https://cr.openjdk.java.net/~shade/8230024/webrev.01/

This is not used, and it is the source of many build failures when WeakProcessor and OopStorage
shapes change a lot. Should be removed for clarity. This blocks the fix for JDK-8229998. I believe
this one should go in separately to be backportable.

Testing: hotspot_gc_shenandoah {fastdebug|release}, grepping around the source code

-- 
Thanks,
-Aleksey