Remove replace/preserve logic from rate of change transformer

The idea is to not re-emit cpu samples from the cpu_pipeline
by default, but instead simplify the pipeline.yaml by allowing
these original samples to be emitted by the general-purpose
pipeline as before, thus avoiding unintended double-publication.

Now only the derived samples would be emitted from the
scaling or rate of change transformers.

Change-Id: I12623181d289fc0ee3cdb6fcdbacf8e76e53d244
Merge "Remove replace/preserve logic from rate of change transformer"