RFR (M) 8232102: Shenandoah: print everything in proper units

[Aleksey Shipilev]

RFE:
  https://bugs.openjdk.java.net/browse/JDK-8232102

Shenandoah is used on smaller heaps as well as large ones. There, the default unit of "M" makes the
logs too coarse and lose information. We have already fixed up some of the uses where it is
critical. This issue handles the rest of the cases. This makes more sense after JDK-8217315 is
fixed. Note the GC timings/heap-sizes themselves are handled by shared code, see JDK-8232100.

Fix:
  https://cr.openjdk.java.net/~shade/8232102/webrev.01/

Testing: hotspot_gc_shenandoah {fastdebug, release}, eyeballing gc logs

-- 
Thanks,
-Aleksey