### 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
String defaultMetric = ((AggregateDoubleMetricFieldMapper.AggregateDoubleMetricFieldType) fieldType).getDefaultMetric().name();
        assertEquals("field." + defaultMetric, fieldExistsQuery.getField());
        assertNoFieldNamesField(fields);
    }
    @Override
    protected Object generateRandomInputValue(MappedFieldType ft) {
        assumeFalse("Test implemented in a follow up", true);
        return null;
    }
    public void testCannotBeUsedInMultifields() {
        Exception e = expectThrows(MapperParsingException.class, () -> createMapperService(fieldMapping(b -> {
            b.field("type", "keyword");
            b.startObject("fields");
            b.startObject("metric");
            minimalMapping(b);
            b.endObject();
            b.endObject();
        })));
        assertThat(e.getMessage(), containsString("Field [metric] of type [aggregate_metric_double] can't be used in multifields"));
    }
    public void testMetricType() throws IOException {
        
        MapperService mapperService = createMapperService(fieldMapping(b -> minimalMapping(b)));
        AggregateDoubleMetricFieldMapper.AggregateDoubleMetricFieldType ft =
            (AggregateDoubleMetricFieldMapper.AggregateDoubleMetricFieldType) mapperService.fieldType("field");
        assertNull(ft.getMetricType());
        assertMetricType("gauge", AggregateDoubleMetricFieldMapper.AggregateDoubleMetricFieldType::getMetricType);
        {
            
            Exception e = expectThrows(MapperParsingException.class, () -> createMapperService(fieldMapping(b -> {