Fix ChineseCLIPModel.get_text_features

[JiangJQ2000]

What does this PR do?

Currently, ChineseCLIPModel.get_text_features will throw the error
TypeError: linear(): argument 'input' (position 1) must be Tensor, not NoneType.
This happens because ChineseCLIPTextModel inside ChineseCLIPModel is instantiated with add_pooling_layer=False, while PR #40555 incorrectly treats its output as BaseModelOutputWithPooling.
Therefore, I reverted the changes related to this part.

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[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: chinese_clip

[zucchini-nlp]

Looks good to me, thanks for fixing

[HuggingFaceDocBuilderDev]

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