We use `totalMetrics` with a `startTimeInNanos` and a call to `postIngest` to track the 'total time' that ingest is running for a given document. You can imagine it's a little stopwatch that we start and stop. Unfortunately, I think we're stopping the stopwatch just a little too soon, on the start side, we include the time spent transforming the document into an `IngestDocument`, but we do not include the (non-negligible) time transforming from an `IngestDocument` after the pipeline logic has run.

That is, the call to `sourceAsMap` is included:

https://github.com/elastic/elasticsearch/blob/d03664f84f15dcfcb900cf2d43121ca9d89bdda8/server/src/main/java/org/elasticsearch/ingest/IngestService.java#L905

But the call to `source` is not:

https://github.com/elastic/elasticsearch/blob/d03664f84f15dcfcb900cf2d43121ca9d89bdda8/server/src/main/java/org/elasticsearch/ingest/IngestService.java#L948

The consequence of this is that the `total` ingest stats doesn't actually reflect the true time spent in ingest code:

```
GET _nodes/stats?filter_path=nodes.*.ingest
{
  "nodes" : {
    "Aysm6ztIRne2ES5ktyuqtw" : {
      "ingest" : {
        "total" : {
          "count" : 1,
          "time_in_millis" : 110, <--- this should be a little higher than it is
```
server/src/main/java/org/elasticsearch/ingest/IngestService.java
return true;
            }
        }
        return false;
    }
    /**
     * Returns the pipeline by the specified id
     */
    public Pipeline getPipeline(String id) {
        PipelineHolder holder = pipelines.get(id);
        if (holder != null) {
            return holder.pipeline;
        } else {
            return null;
        }
    }
    public Map<String, Processor.Factory> getProcessorFactories() {
        return processorFactories;
    }
    @Override
    public IngestInfo info() {
        Map<String, Processor.Factory> processorFactories = getProcessorFactories();
        List<ProcessorInfo> processorInfoList = new ArrayList<>(processorFactories.size());
        for (Map.Entry<String, Processor.Factory> entry : processorFactories.entrySet()) {
            processorInfoList.add(new ProcessorInfo(entry.getKey()));
        }
        return new IngestInfo(processorInfoList);
    }
    Map<String, PipelineHolder> pipelines() {
        return pipelines;