Remove old out-dated TODO (#92275)

test/framework/src/main/java/org/elasticsearch/index/mapper/MapperTestCase.java

@@ -388,8 +388,7 @@ public abstract class MapperTestCase extends MapperServiceTestCase {
         assertParseMinimalWarnings();
     }
 
-    // TODO make this final once we remove FieldMapperTestCase2
-    public void testMinimalToMaximal() throws IOException {
+    public final void testMinimalToMaximal() throws IOException {
         XContentBuilder orig = JsonXContent.contentBuilder().startObject();
         createMapperService(fieldMapping(this::minimalMapping)).documentMapper().mapping().toXContent(orig, INCLUDE_DEFAULTS);
         orig.endObject();