Revert "Enable useOneOfInterfaces for the ruby generator (#8061)" (#9104)

This reverts commit 23bc2aaf6b.

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -622,7 +622,6 @@ public class DefaultCodegen implements CodegenConfig {
      *
      * @param objs Map of models
      * @return maps of models with better enum support
-     * 
      */
     public Map<String, Object> postProcessModelsEnum(Map<String, Object> objs) {
         List<Object> models = (List<Object>) objs.get("models");
@@ -6474,7 +6473,6 @@ public class DefaultCodegen implements CodegenConfig {
         cm.classname = type;
         cm.vendorExtensions.put("x-is-one-of-interface", true);
         cm.interfaceModels = new ArrayList<CodegenModel>();
-        cm.classFilename = toModelFilename(type);
 
         addOneOfInterfaces.add(cm);
     }

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/RubyClientCodegen.java

@@ -92,7 +92,6 @@ public class RubyClientCodegen extends AbstractRubyCodegen {
         );
 
         supportsInheritance = true;
-        useOneOfInterfaces = true;
 
         // clear import mapping (from default generator) as ruby does not use it
         // at the moment