call_method() now uses _PyObject_FastCall()

Issue #29233: Replace the inefficient _PyObject_VaCallFunctionObjArgs() with
_PyObject_FastCall() in call_method() and call_maybe().

Only a few functions call call_method() and call it with a fixed number of
arguments. Avoid the complex and expensive _PyObject_VaCallFunctionObjArgs()
function, replace it with an array allocated on the stack with the exact number
of argumlents.

It reduces the stack consumption, bytes per call, before => after:

test_python_call: 1168 => 1152 (-16 B)
test_python_getitem: 1344 => 1008 (-336 B)
test_python_iterator: 1568 => 1232 (-336 B)

Remove the _PyObject_VaCallFunctionObjArgs() function which became useless.
Rename it to object_vacall() and make it private.

Include/abstract.h

@@ -323,14 +323,6 @@ PyAPI_FUNC(PyObject *) _PyObject_CallMethodId_SizeT(PyObject *obj,
 PyAPI_FUNC(PyObject *) PyObject_CallFunctionObjArgs(PyObject *callable,
                                                     ...);
 
-#ifndef Py_LIMITED_API
-/* Similar PyObject_CallFunctionObjArgs(), but pass positional arguments
-   as a va_list: list of PyObject* object. */
-PyAPI_FUNC(PyObject *) _PyObject_VaCallFunctionObjArgs(
-    PyObject *callable,
-    va_list vargs);
-#endif
-
 /* Call the method named 'name' of object 'obj' with a variable number of
    C arguments.  The C arguments are provided as PyObject* values, terminated
    by NULL.