### 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_
test/framework/src/main/java/org/elasticsearch/index/mapper/MapperTestCase.java
assertThat(checker.apply(fieldType).name(), equalTo(metricType));
    }
    public final void testEmptyName() {
        MapperParsingException e = expectThrows(MapperParsingException.class, () -> createMapperService(mapping(b -> {
            b.startObject("");
            minimalMapping(b);
            b.endObject();
        })));
        assertThat(e.getMessage(), containsString("field name cannot be an empty string"));
    }
    public final void testBlankName() {
        Version version = getVersion();
        assumeTrue("blank field names are rejected from 8.6.0 onwards", version.onOrAfter(Version.V_8_6_0));
        MapperParsingException e = expectThrows(MapperParsingException.class, () -> createMapperService(version, mapping(b -> {
            b.startObject("  ");
            minimalMapping(b);
            b.endObject();
        })));
        assertThat(e.getMessage(), containsString("field name cannot contain only whitespaces"));
    }
    public final void testMinimalSerializesToItself() throws IOException {
        XContentBuilder orig = JsonXContent.contentBuilder().startObject();
        createMapperService(fieldMapping(this::minimalMapping)).documentMapper().mapping().toXContent(orig, ToXContent.EMPTY_PARAMS);
        orig.endObject();
        XContentBuilder parsedFromOrig = JsonXContent.contentBuilder().startObject();
        createMapperService(orig).documentMapper().mapping().toXContent(parsedFromOrig, ToXContent.EMPTY_PARAMS);
        parsedFromOrig.endObject();
        assertEquals(Strings.toString(orig), Strings.toString(parsedFromOrig));
        assertParseMinimalWarnings();
    }