### 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
.errorMatches("failed to parse field [field.value_count] of type [integer]")
        );
    }
    @Override
    protected String[] ignoredFields() {
        return new String[] { "field.value_count", "field.min", "field.max" };
    }
    /**
     * Test adding a metric that other than the supported ones (min, max, sum, value_count)
     */
    public void testUnsupportedMetric() throws Exception {
        Exception e = expectThrows(
            MapperParsingException.class,
            () -> createDocumentMapper(
                fieldMapping(b -> b.field("type", CONTENT_TYPE).field(METRICS_FIELD, new String[] { "min", "max", "unsupported" }))
            )
        );
        assertThat(e.getMessage(), containsString("Metric [unsupported] is not supported."));
    }
    /**
     * Test parsing a value_count metric written as double with zero decimal digits
     */
    public void testValueCountDouble() throws Exception {
        DocumentMapper mapper = createDocumentMapper(fieldMapping(this::minimalMapping));
        ParsedDocument doc = mapper.parse(
            source(b -> b.startObject("field").field("min", 10.0).field("max", 50.0).field("value_count", 77.0).endObject())
        );
        assertEquals(77, doc.rootDoc().getField("field.value_count").numericValue().longValue());
    }
    /**