refactor: remove bySelf method

npm/ng-packs/packages/core/src/lib/services/track-by.service.ts

@@ -12,8 +12,4 @@ export class TrackByService<ItemType = any> {
   byDeep<T = ItemType>(...keys: T extends object ? O.Paths<T> : never): TrackByFunction<T> {
     return (_, item) => keys.reduce((acc, key) => acc[key], item);
   }
-
-  bySelf<T = ItemType>(): TrackByFunction<T> {
-    return (_, item) => item;
-  }
 }

npm/ng-packs/packages/core/src/lib/tests/track-by.service.spec.ts

@@ -18,10 +18,4 @@ describe('TrackByService', () => {
       expect(service.byDeep<typeof obj>('a', 'b', 'c', 'x')(284, obj)).toBe(1036);
     });
   });
-
-  describe('#bySelf', () => {
-    it('should return a function which tracks the item', () => {
-      expect(service.bySelf()(284, 'X')).toBe('X');
-    });
-  });
 });