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
"Failed to generate the source document for ingest pipeline [" + pipeline.getId() + "]",
                                ex
                            )
                        );
                        return;
                    }
                    Map<String, String> map;
                    if ((map = metadata.getDynamicTemplates()) != null) {
                        Map<String, String> mergedDynamicTemplates = new HashMap<>(indexRequest.getDynamicTemplates());
                        mergedDynamicTemplates.putAll(map);
                        indexRequest.setDynamicTemplates(mergedDynamicTemplates);
                    }
                    postIngest(ingestDocument, indexRequest);
                    handler.accept(null);
                }
            }
        });
    }
    private void postIngest(IngestDocument ingestDocument, IndexRequest indexRequest) {
        
        Object rawTimestamp = ingestDocument.getSourceAndMetadata().get(TimestampField.FIXED_TIMESTAMP_FIELD);
        if (rawTimestamp != null && indexRequest.getRawTimestamp() == null) {
            indexRequest.setRawTimestamp(rawTimestamp);
        }
    }
    @Override
    public void applyClusterState(final ClusterChangedEvent event) {
        state = event.state();
        if (state.blocks().hasGlobalBlock(GatewayService.STATE_NOT_RECOVERED_BLOCK)) {
            return;