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
indexRequest.setPipeline(NOOP_PIPELINE_NAME);
                    final String finalPipelineId = indexRequest.getFinalPipeline();
                    indexRequest.setFinalPipeline(NOOP_PIPELINE_NAME);
                    boolean hasFinalPipeline = true;
                    final List<String> pipelines;
                    if (IngestService.NOOP_PIPELINE_NAME.equals(pipelineId) == false
                        && IngestService.NOOP_PIPELINE_NAME.equals(finalPipelineId) == false) {
                        pipelines = List.of(pipelineId, finalPipelineId);
                    } else if (IngestService.NOOP_PIPELINE_NAME.equals(pipelineId) == false) {
                        pipelines = List.of(pipelineId);
                        hasFinalPipeline = false;
                    } else if (IngestService.NOOP_PIPELINE_NAME.equals(finalPipelineId) == false) {
                        pipelines = List.of(finalPipelineId);
                    } else {
                        if (counter.decrementAndGet() == 0) {
                            onCompletion.accept(originalThread, null);
                        }
                        assert counter.get() >= 0;
                        i++;
                        continue;
                    }
                    executePipelines(
                        i,
                        pipelines.iterator(),
                        hasFinalPipeline,
                        indexRequest,
                        onDropped,
                        onFailure,
                        counter,
                        onCompletion,