CPUTimeCounters unconditionally creates CPUTimeGroups::CPUTimeType::gc_total. Since only Parallel and G1 are supported by this framework/class, this leads to publishing a counter that always resolves to 0. This may be contradictory for an end-user especially so as we now support logging GC CPU time for any GC inside Hotspot. For an example using -Xlog:cpu we get

```
[7.907s][info][cpu] === CPU time Statistics =============================================================
[7.907s][info][cpu] CPUs
[7.907s][info][cpu] s % utilized
[7.907s][info][cpu] Process
[7.907s][info][cpu] Total 186.9562 100.00 23.6
[7.907s][info][cpu] Garbage Collection 0.6700 0.36 0.1
[7.907s][info][cpu] GC Threads 0.6692 0.36 0.1
[7.907s][info][cpu] VM Thread 0.0008 0.00 0.0
[7.907s][info][cpu] =====================================================================================
```

But `jcmd $(pgrep -n java) PerfCounter.print | grep -E "sun.threads.total_gc_cpu_time"` prints (in this case for ZGC): `sun.threads.total_gc_cpu_time=0`.