The `ignore_malformed` option is supported by a few of our field types, mainly numerics and dates, to still accept the document when such fields hold malformed values. See https://www.elastic.co/guide/en/elasticsearch/reference/current/ignore-malformed.html. Also `ignore_malformed` is an index level setting that gets applied to all field types that support it. 

The boolean field type does not support `ignore_malformed` but it should, so that if a boolean field cannot be parsed as a boolean, the document can still be accepted.


server/src/test/java/org/elasticsearch/index/mapper/BooleanFieldMapperTests.java
b.field("doc_values", false);
        }));
        assertAggregatableConsistency(mapperService.fieldType("field"));
    }
    public void testDefaults() throws IOException {
        MapperService mapperService = createMapperService(fieldMapping(this::minimalMapping));
        ParsedDocument doc = mapperService.documentMapper().parse(source(this::writeField));
        withLuceneIndex(mapperService, iw -> iw.addDocument(doc.rootDoc()), reader -> {
            final LeafReader leaf = reader.leaves().get(0).reader();
            
            assertEquals(new BytesRef("T"), leaf.terms("field").iterator().next());
            SortedNumericDocValues values = leaf.getSortedNumericDocValues("field");
            assertNotNull(values);
            assertTrue(values.advanceExact(0));
            assertEquals(1, values.docValueCount());
            assertEquals(1, values.nextValue());
        });
    }
    public void testSerialization() throws IOException {
        DocumentMapper defaultMapper = createDocumentMapper(fieldMapping(this::minimalMapping));
        Mapper mapper = defaultMapper.mappers().getMapper("field");
        XContentBuilder builder = XContentFactory.jsonBuilder().startObject();
        mapper.toXContent(builder, ToXContent.EMPTY_PARAMS);
        builder.endObject();
        assertEquals("""
            {"field":{"type":"boolean"}}""", Strings.toString(builder));
        
        defaultMapper = createDocumentMapper(fieldMapping(b -> {
            b.field("type", "boolean");
            b.field("doc_values", false);