### Elasticsearch Version

main

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

all

### Problem Description

When you configure an `aggregate_metric_double` with `ignore_malformed: true` and send a malformed value we create an `_ignored` field with three values, `field.value_count`, `field.min`, and `field.max`. This is the only top "composite" field that creates `_ignored` values for its children. Things like shape only create `field` in `_ignored`. Is there a good reason for `aggregate_metric_double` to be different?

### Steps to Reproduce

see above

### Logs (if relevant)

_No response_
x-pack/plugin/mapper-aggregate-metric/src/test/java/org/elasticsearch/xpack/aggregatemetric/mapper/AggregateDoubleMetricFieldMapperTests.java
value.put(m.name(), randomDoubleBetween(-1_000_000d, 99d, false));
                } else {
                    value.put(m.name(), randomDouble());
                }
            }
            return value;
        }
        private void mapping(XContentBuilder b) throws IOException {
            String[] metrics = storedMetrics.stream().map(Metric::toString).toArray(String[]::new);
            b.field("type", CONTENT_TYPE).array(METRICS_FIELD, metrics).field(DEFAULT_METRIC, metrics[0]);
        }
        @Override
        public List<SyntheticSourceInvalidExample> invalidExample() throws IOException {
            return List.of(
                new SyntheticSourceInvalidExample(
                    matchesPattern("field \\[field] of type \\[.+] doesn't support synthetic source because it ignores malformed numbers"),
                    b -> {
                        mapping(b);
                        b.field("ignore_malformed", true);
                    }
                )
            );
        }
    }
    @Override
    protected boolean supportsCopyTo() {
        return false;
    }
}