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
if (newPipelines == null) {
                    newPipelines = new HashMap<>(existingPipelines);
                }
                newPipelines.remove(entry.getKey());
            }
        }
        if (newPipelines != null) {
            
            this.pipelines = Map.copyOf(newPipelines);
            
            if (exceptions != null) {
                ExceptionsHelper.rethrowAndSuppress(exceptions);
            }
        }
    }
    /**
     * Gets all the Processors of the given type from within a Pipeline.
     * @param pipelineId the pipeline to inspect
     * @param clazz the Processor class to look for
     * @return True if the pipeline contains an instance of the Processor class passed in
     */
    public <P extends Processor> List<P> getProcessorsInPipeline(String pipelineId, Class<P> clazz) {
        Pipeline pipeline = getPipeline(pipelineId);
        if (pipeline == null) {
            throw new IllegalArgumentException("pipeline with id [" + pipelineId + "] does not exist");
        }
        List<P> processors = new ArrayList<>();
        for (Processor processor : pipeline.flattenAllProcessors()) {
            if (clazz.isAssignableFrom(processor.getClass())) {
                processors.add(clazz.cast(processor));