fix super().__call__ calls in constructors_call_metaclass

[carljm]

These calls were incorrect as written, they wrongly included the explicit cls arg, even though this is bound into the descriptor lookup; __call__ is a regular method, not a static method like __new__. At runtime, the examples as written would succeed with no argument (cls would be passed as x) and fail with a single argument (two arguments passed where only one is expected).

This wasn't caught by type checkers (and has no impact on the conformance results) because the use of *args, **kwargs means type checkers can't track the correct arity or argument types through the metaclass __call__.

Incorrect version (main branch):

>>> class Meta3(type):
...     def __call__(cls, *args, **kwargs):
...         return super().__call__(cls, *args, **kwargs)
...
>>> class Class3(metaclass=Meta3):
...     def __new__(cls, x: int):
...         return super().__new__(cls)
...
>>> Class3()
<__main__.Class3 object at 0x102890ad0>
>>> Class3(1)
Traceback (most recent call last):
  File "<python-input-5>", line 1, in <module>
    Class3(1)
    ~~~~~~^^^
  File "<python-input-2>", line 3, in __call__
    return super().__call__(cls, *args, **kwargs)
           ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
TypeError: Class3.__new__() takes 2 positional arguments but 3 were given

Fixed version (this PR):

>>> class Meta3(type):
...     def __call__(cls, *args, **kwargs):
...         return super().__call__(*args, **kwargs)
...
>>> class Class3(metaclass=Meta3):
...     def __new__(cls, x: int):
...         return super().__new__(cls)
...
>>> Class3()
Traceback (most recent call last):
  File "<python-input-8>", line 1, in <module>
    Class3()
    ~~~~~~^^
  File "<python-input-6>", line 3, in __call__
    return super().__call__(*args, **kwargs)
           ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
TypeError: Class3.__new__() missing 1 required positional argument: 'x'
>>> Class3(1)
<__main__.Class3 object at 0x102890c20>