fix(time-picker): remove the default value of the size prop

[kkkisme]

Types of changes

• [ ] New feature
• [x] Bug fix
• [ ] Enhancement
• [ ] Component style change
• [ ] Typescript definition change
• [ ] Documentation change
• [ ] Coding style change
• [ ] Refactoring
• [ ] Test cases
• [ ] Continuous integration
• [ ] Breaking change
• [ ] Others

Background and context

#1509

Solution

How is the change tested?

Changelog

Component	Changelog(CN)	Changelog(EN)	Related issues
time-picker	修复 time-picker size 的默认值	fix time-picker default size	#1509

Checklist:

• [ ] Test suite passes (npm run test)
• [ ] Provide changelog for relevant changes (e.g. bug fixes and new features) if applicable.
• [ ] Changes are submitted to the appropriate branch (e.g. features should be submitted to feature branch and others should be submitted to main branch)

Other information

[hehehai]

@kkkisme 😅 抱歉，我先前没看 useFormItem 的实现。这里不需要这么复杂，是 size 默认参数的问题。

1. 删除 default 参数（不需要，内部组件 size hook 会处理默认值） https://github.com/arco-design/arco-design-vue/blob/f3db85c5df656c2959e491181e2821ff0a644b75/packages/web-vue/components/time-picker/time-picker.vue#L200-L205

2. 在 form demo 文件中补充 time-picker 的例子 https://github.com/arco-design/arco-design-vue/blob/f3db85c5df656c2959e491181e2821ff0a644b75/packages/web-vue/components/form/demo/validation.md?plain=1#L61-L69

<a-form-item field="date" label="Date">
···
<a-form-item field="time" label="Time">
      <a-time-picker v-model="form.time" placeholder="Please select ..."/>
</a-form-item>
···

就可以了 😊

[hehehai]

@kkkisme 🥰，麻烦把 commit 整理成一个，提交一下，方便 pr 的归档 🤝 （也可关了这个pr，再提交一个新的😊，pr名称建议使用 fix-date-picker-default-size）

[kkkisme]

@kkkisme 🥰，麻烦把 commit 整理成一个，提交一下，方便 pr 的归档 🤝 （也可关了这个pr，再提交一个新的😊，pr名称建议使用 fix-date-picker-default-size）

👌