[Fix] Fix placement policy in ColossalAIStrategy

[fanqiNO1]

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Motivation

placement_policy in ColossalAIStrategy must be auto or static when using ColossalAI==0.3.4.

https://github.com/hpcaitech/ColossalAI/blob/main/colossalai/zero/gemini/placement_policy.py#L202

Modification

Please briefly describe what modification is made in this PR.

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repos?
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Use cases (Optional)

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Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. If the modification has potential influence on downstream projects, this PR should be tested with downstream projects, like MMDetection or MMPretrain.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[zhouzaida]

keep the CollosalAIModelWrapper to avoid bc and also register it to MODEL_WRAPPERS