set tp_new from the class in the hierarchy that actually owns the descriptor (closes #25731)

Debugging by Eryk Sun.

Lib/test/test_descr.py

@@ -4564,6 +4564,14 @@ order (MRO) for bases """
         self.assertRegex(repr(method),
             r"<bound method qualname of <object object at .*>>")
 
+    def test_deleting_new_in_subclasses(self):
+        class X:
+            def __init__(self, a):
+                pass
+        X.__new__ = None
+        del X.__new__
+        X(1) # should work
+
 
 class DictProxyTests(unittest.TestCase):
     def setUp(self):