[Dy2St]Refine AnnAssign in static_analysis

[0x45f]

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Describe

之前在动转静中使用a: int = b类似的type hint语句时，如果static analysis模块分析出a的标注类型和b的类型不同，则会将a分析为b的类型，而不会使用标注的类型int。但是static analysis模块有时后会将b分析为unknow类型，导致a的类型也被分析为unknow，使得type hint失效。

@paddle.jit.to_static
def func(x):
    a = []
    import pdb; pdb.set_trace()
    x = paddle.to_tensor(x)
    tmp: paddle.Tensor = len(x)
    for i in range(tmp):
        a.append(i)

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