### 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
)
        );
        assertThat(doc.rootDoc().getField("field.subfield.min"), notNullValue());
    }
    /**
     *  subfields of aggregate_metric_double should not be searchable or exposed in field_caps
     */
    public void testNoSubFieldsIterated() throws IOException {
        Metric[] values = Metric.values();
        List<Metric> subset = randomSubsetOf(randomIntBetween(1, values.length), values);
        DocumentMapper mapper = createDocumentMapper(
            fieldMapping(b -> b.field("type", CONTENT_TYPE).field(METRICS_FIELD, subset).field(DEFAULT_METRIC, subset.get(0)))
        );
        Iterator<Mapper> iterator = mapper.mappers().getMapper("field").iterator();
        assertFalse(iterator.hasNext());
    }
    public void testFieldCaps() throws IOException {
        MapperService aggMetricMapperService = createMapperService(fieldMapping(this::minimalMapping));
        MappedFieldType fieldType = aggMetricMapperService.fieldType("field");
        assertThat(fieldType.familyTypeName(), equalTo("aggregate_metric_double"));
        assertTrue(fieldType.isSearchable());
        assertTrue(fieldType.isAggregatable());
    }
    /*
     * Since all queries for aggregate_metric_double fields are delegated to their default_metric numeric
     *  sub-field, we override this method so that testExistsQueryMinimalMapping() passes successfully.
     */
    protected void assertExistsQuery(MappedFieldType fieldType, Query query, LuceneDocument fields) {
        assertThat(query, Matchers.instanceOf(FieldExistsQuery.class));
        FieldExistsQuery fieldExistsQuery = (FieldExistsQuery) query;