### 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
case 1 -> b.field("max", 60);
                case 2 -> b.field("value_count", 2);
                case 3 -> b.field("sum", 200.0);
            }
            b.endObject().endArray();
        })));
        assertThat(
            e.getCause().getMessage(),
            containsString(
                "Field [field] of type [aggregate_metric_double] "
                    + "does not support indexing multiple values for the same field in the same document"
            )
        );
    }
    /**
     * Test setting the default_metric explicitly
     */
    public void testExplicitDefaultMetric() throws Exception {
        DocumentMapper mapper = createDocumentMapper(
            fieldMapping(
                b -> b.field("type", CONTENT_TYPE).field(METRICS_FIELD, new String[] { "value_count", "sum" }).field(DEFAULT_METRIC, "sum")
            )
        );
        Mapper fieldMapper = mapper.mappers().getMapper("field");
        assertThat(fieldMapper, instanceOf(AggregateDoubleMetricFieldMapper.class));
        assertEquals(Metric.sum, ((AggregateDoubleMetricFieldMapper) fieldMapper).defaultMetric());
    }
    /**
     * Test the default_metric when not set explicitly. When only a single metric is contained, this is set as the default
     */