[Sprint: 38] XD-2107&1048: --nameExpression for metrics & --incrementExpression for agg-counter

The logic for smoothing has always been in the gauge itself, it's just that before there was a method on the repository that made the client think that it was taking care of it. I chose to remove it (as well as the indirection through MetricUtils which was not needed anymore, from the era where we merged "repository" and "service" IIRC)