### Elasticsearch Version

main

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

all

### Problem Description

The `filter` agg should run as `filters` because the `filters` agg has tons of optimizations, some of them are even around when running with a single filter. At a minimum we should optimize the `filter` agg in the same way as `filters`, but I think it's easier if we just run it as `filters`.

### Steps to Reproduce

see above

### Logs (if relevant)

_No response_
server/src/test/java/org/elasticsearch/search/aggregations/bucket/filter/FilterAggregatorTests.java
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.store.Directory;
import org.apache.lucene.tests.index.RandomIndexWriter;
import org.elasticsearch.index.mapper.KeywordFieldMapper;
import org.elasticsearch.index.mapper.MappedFieldType;
import org.elasticsearch.index.query.MatchAllQueryBuilder;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.aggregations.AggregationExecutionContext;
import org.elasticsearch.search.aggregations.Aggregator.BucketComparator;
import org.elasticsearch.search.aggregations.AggregatorTestCase;
import org.elasticsearch.search.aggregations.LeafBucketCollector;
import org.elasticsearch.search.aggregations.support.AggregationInspectionHelper;
import org.elasticsearch.search.sort.SortOrder;
import org.junit.Before;
import java.io.IOException;
import static java.util.Collections.singleton;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.greaterThan;
import static org.hamcrest.Matchers.lessThan;
public class FilterAggregatorTests extends AggregatorTestCase {
    private MappedFieldType fieldType;
    @Before
    public void setUpTest() throws Exception {
        super.setUp();
        fieldType = new KeywordFieldMapper.KeywordFieldType("field");