### 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(doc.docs().get(0).getFields("_field_names").length, equalTo(0));
        } else {
            expectThrows(MapperParsingException.class, () -> mapper.parse(source(b -> b.nullField("field"))));
        }
        assertWarnings(getParseMinimalWarnings());
    }
    protected boolean allowsNullValues() {
        return true;
    }
    public final void testMinimalIsInvalidInRoutingPath() throws IOException {
        MapperService mapper = createMapperService(fieldMapping(this::minimalMapping));
        try {
            IndexSettings settings = createIndexSettings(
                Version.CURRENT,
                Settings.builder()
                    .put(IndexSettings.MODE.getKey(), "time_series")
                    .put(IndexMetadata.INDEX_ROUTING_PATH.getKey(), "field")
                    .put(IndexSettings.TIME_SERIES_START_TIME.getKey(), "2021-04-28T00:00:00Z")
                    .put(IndexSettings.TIME_SERIES_END_TIME.getKey(), "2021-04-29T00:00:00Z")
                    .build()
            );
            Exception e = expectThrows(IllegalArgumentException.class, () -> mapper.documentMapper().validate(settings, false));
            assertThat(e.getMessage(), equalTo(minimalIsInvalidRoutingPathErrorMessage(mapper.mappingLookup().getMapper("field"))));
        } finally {
            assertParseMinimalWarnings();
        }
    }
    protected String minimalIsInvalidRoutingPathErrorMessage(Mapper mapper) {
        return "All fields that match routing_path must be keywords with [time_series_dimension: true] "
            + "and without the [script] parameter. ["