__getitem__ as a property doesn't evaluate typing of __get__

[adhami3310]

Similar to #9574 which fixed it for some dunder methods, but not for __getitem__ (not sure how many others?).

Example code:

from __future__ import annotations

from typing_extensions import Self, TypeVar, overload, TypeVarTuple

S = TypeVar("S")
R = TypeVarTuple("R")


class Function[*T]:
    def __init__(self, *prefilled_args):
        self.prefilled_args = prefilled_args

    def __call__(self, *args: *T) -> None:
        print(f"{self.prefilled_args + args=}")

    def partial_once[S, *R](self: Function[S, *R], arg: S) -> Function[*R]:
        return Function(*self.prefilled_args, arg)

    @overload
    def __get__(self, instance: None, owner) -> Self: ...

    @overload
    def __get__(self: Function[S, *R], instance: S, owner) -> Function[*R]: ...

    def __get__(self, instance, owner):
        if instance is None:
            return self
        return self.partial_once(instance)


class ArrayLike:
    __getitem__ = Function[Self, int]()


x = ArrayLike().__getitem__(1)
y = ArrayLike()[1]

The second line should be identical to the first, but the type system doesn't evaluate the __get__.