<!-- Thanks for sending a pull request! Here are some tips for you:
1. 如果这是你的第一次，请阅读我们的贡献指南：<https://github.com/halo-dev/halo/blob/main/CONTRIBUTING.md>。
1. If this is your first time, please read our contributor guidelines: <https://github.com/halo-dev/halo/blob/main/CONTRIBUTING.md>.
2. 请根据你解决问题的类型为 Pull Request 添加合适的标签。
2. Please label this pull request according to what type of issue you are addressing, especially if this is a release targeted pull request.
3. 请确保你已经添加并运行了适当的测试。
3. Ensure you have added or ran the appropriate tests for your PR.
-->
#### What type of PR is this?
<!--
添加其中一个类别：
Add one of the following kinds:
/kind bug
/kind cleanup
/kind documentation
/kind feature
/kind improvement
适当添加其中一个或多个类别（可选）：
Optionally add one or more of the following kinds if applicable:
/kind api-change
/kind deprecation
/kind failing-test
/kind flake
/kind regression
-->
/area ui
/kind improvement
#### What this PR does / why we need it:
当前多选框disabled与非disabled样式上无区别，不好分辨。
#### Which issue(s) this PR fixes:
<!--
PR 合并时自动关闭 issue。
Automatically closes linked issue when PR is merged.
用法：`Fixes #<issue 号>`，或者 `Fixes (粘贴 issue 完整链接)`
Usage: `Fixes #<issue number>`, or `Fixes (paste link of issue)`.
-->
Fixes https://github.com/halo-dev/halo/issues/5974
#### Special notes for your reviewer:
#### Does this PR introduce a user-facing change?
<!--
如果当前 Pull Request 的修改不会造成用户侧的任何变更，在 `release-note` 代码块儿中填写 `NONE`。
否则请填写用户侧能够理解的 Release Note。如果当前 Pull Request 包含破坏性更新（Break Change），
Release Note 需要以 `action required` 开头。
If no, just write "NONE" in the release-note block below.
If yes, a release note is required:
Enter your extended release note in the block below. If the PR requires additional action from users switching to the new release, include the string "action required".
-->
```release-note
增加多选框disabled样式
```
Ryan Wang