refactor(ivy): revert onChanges change back to a feature (#28187)

- adds fixmeIvy annotation to tests that should remain updated so we can resolve those issues in the subsequent commits

PR Close #28187

packages/compiler/src/render3/r3_identifiers.ts

@@ -188,6 +188,8 @@ export class Identifiers {
   static registerContentQuery:
       o.ExternalReference = {name: 'ɵregisterContentQuery', moduleName: CORE};
 
+  static NgOnChangesFeature: o.ExternalReference = {name: 'ɵNgOnChangesFeature', moduleName: CORE};
+
   static InheritDefinitionFeature:
       o.ExternalReference = {name: 'ɵInheritDefinitionFeature', moduleName: CORE};