supported field type tests for max agg (elastic#53701)

Adds test hooks for testing supported ValuesSource types for the max
aggregation

server/src/test/java/org/elasticsearch/search/aggregations/metrics/MaxAggregatorTests.java

@@ -71,7 +71,9 @@
 import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregationBuilder;
 import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregator;
 import org.elasticsearch.search.aggregations.support.AggregationInspectionHelper;
+import org.elasticsearch.search.aggregations.support.CoreValuesSourceType;
 import org.elasticsearch.search.aggregations.support.ValueType;
+import org.elasticsearch.search.aggregations.support.ValuesSourceType;
 import org.elasticsearch.search.lookup.LeafDocLookup;
 
 import java.io.IOException;
@@ -89,6 +91,7 @@
 
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singleton;
+import static java.util.Collections.singletonList;
 import static org.elasticsearch.index.query.QueryBuilders.termQuery;
 import static org.hamcrest.Matchers.equalTo;
 
@@ -158,6 +161,17 @@ protected ScriptService getMockScriptService() {
         return new ScriptService(Settings.EMPTY, engines, ScriptModule.CORE_CONTEXTS);
     }
 
+    @Override
+    protected List<ValuesSourceType> getSupportedValuesSourceTypes() {
+        return singletonList(CoreValuesSourceType.NUMERIC);
+    }
+
+    @Override
+    protected AggregationBuilder createAggBuilderForTypeTest(MappedFieldType fieldType, String fieldName) {
+        return new MaxAggregationBuilder("_name")
+            .field(fieldName);
+    }
+
     public void testNoDocs() throws IOException {
         testCase(new MatchAllDocsQuery(), iw -> {
             // Intentionally not writing any docs