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
* these cases as we need to reject the request if the pipeline was set by a required pipeline and there is a request
             * pipeline parameter too.
             */
            indexRequest.isPipelineResolved(true);
        }
        
        return NOOP_PIPELINE_NAME.equals(indexRequest.getPipeline()) == false
            || NOOP_PIPELINE_NAME.equals(indexRequest.getFinalPipeline()) == false;
    }
    public ClusterService getClusterService() {
        return clusterService;
    }
    public ScriptService getScriptService() {
        return scriptService;
    }
    /**
     * Deletes the pipeline specified by id in the request.
     */
    public void delete(DeletePipelineRequest request, ActionListener<AcknowledgedResponse> listener) {
        clusterService.submitStateUpdateTask(
            "delete-pipeline-" + request.getId(),
            new DeletePipelineClusterStateUpdateTask(listener, request),
            ClusterStateTaskConfig.build(Priority.NORMAL, request.masterNodeTimeout()),
            PIPELINE_TASK_EXECUTOR
        );
    }
    /**
     * Used by this class and {@link org.elasticsearch.action.ingest.ReservedPipelineAction}
     */
    public static class DeletePipelineClusterStateUpdateTask extends PipelineClusterStateUpdateTask {