There's a little buglet in #85387 (which was the PR that closed #84046), specifically, it doesn't account for the possibility that there's both a default/request **and** and a final pipeline, and that they can both touch the `@timestamp` field.

`IngestService#postIngest` was added in #85387, and it's intended that the logic there only runs **once**, after all the pipelines associated with the request have been executed. But as it's currently written, the logic actually runs after each individual pipeline runs.

The consequence of that is that if there's a default/request and a final pipeline in use for a document, and the final pipeline changes the timestamp field, the `rawTimestamp` recorded for the `IndexRequest` associated with the document will mistakenly use the value it sees after the default/request pipeline runs, and **not** the most correct one (from after when the final pipeline runs).

/cc @martijnvg 
server/src/main/java/org/elasticsearch/ingest/IngestDocument.java
}
    /**
     * Checks whether the document contains a value for the provided path
     * @param path The path within the document in dot-notation
     * @return true if the document contains a value for the field, false otherwise
     * @throws IllegalArgumentException if the path is null, empty or invalid.
     */
    public boolean hasField(String path) {
        return hasField(path, false);
    }
    /**
     * Checks whether the document contains a value for the provided path
     * @param path The path within the document in dot-notation
     * @param failOutOfRange Whether to throw an IllegalArgumentException if array is accessed outside of its range
     * @return true if the document contains a value for the field, false otherwise
     * @throws IllegalArgumentException if the path is null, empty or invalid.
     */
    public boolean hasField(String path, boolean failOutOfRange) {
        FieldPath fieldPath = new FieldPath(path);
        Object context = fieldPath.initialContext;
        for (int i = 0; i < fieldPath.pathElements.length - 1; i++) {
            String pathElement = fieldPath.pathElements[i];
            if (context == null) {
                return false;
            }
            if (context instanceof Map<?, ?> map) {
                context = map.get(pathElement);
            } else if (context instanceof List<?> list) {
                try {
                    int index = Integer.parseInt(pathElement);