新建云脑2训练任务页面数据集下拉框显示提示文字“请选择数据集”

新建云脑2训练任务页面，数据集下拉框，当前是默认选中第一个。
改成提示文字“请选择数据集”，让用户去选择。

已合并，可测试。

通过测试，关闭此单。

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Dear OpenI User

Thank you for your continuous support to the Openl Qizhi Community AI Collaboration Platform. In order to protect your usage rights and ensure network security, we updated the Openl Qizhi Community AI Collaboration Platform Usage Agreement in January 2024. The updated agreement specifies that users are prohibited from using intranet penetration tools. After you click "Agree and continue", you can continue to use our services. Thank you for your cooperation and understanding.

For more agreement content, please refer to the《Openl Qizhi Community AI Collaboration Platform Usage Agreement》

#690 新建云脑2训练任务页面数据集下拉框显示提示文字“请选择数据集”