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
final String requestPipeline = indexRequest.getPipeline();
            indexRequest.setPipeline(NOOP_PIPELINE_NAME);
            indexRequest.setFinalPipeline(NOOP_PIPELINE_NAME);
            String defaultPipeline = null;
            String finalPipeline = null;
            IndexMetadata indexMetadata = null;
            
            if (originalRequest != null) {
                indexMetadata = metadata.indices()
                    .get(IndexNameExpressionResolver.resolveDateMathExpression(originalRequest.index(), epochMillis));
            }
            
            if (indexMetadata == null && indexRequest.index() != null) {
                IndexAbstraction indexAbstraction = metadata.getIndicesLookup().get(indexRequest.index());
                if (indexAbstraction != null && indexAbstraction.getWriteIndex() != null) {
                    indexMetadata = metadata.index(indexAbstraction.getWriteIndex());
                }
            }
            
            if (indexMetadata == null && originalRequest != null && originalRequest.index() != null) {
                IndexAbstraction indexAbstraction = metadata.getIndicesLookup().get(originalRequest.index());
                if (indexAbstraction != null && indexAbstraction.getWriteIndex() != null) {
                    indexMetadata = metadata.index(indexAbstraction.getWriteIndex());
                }
            }
            if (indexMetadata != null) {
                final Settings indexSettings = indexMetadata.getSettings();
                if (IndexSettings.DEFAULT_PIPELINE.exists(indexSettings)) {
                    
                    defaultPipeline = IndexSettings.DEFAULT_PIPELINE.get(indexSettings);