bug(SelectGeneric): add dropdown-menu-body class

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Describe the bug

丢失最大高度

### Expected Behavior

下拉框有滚动条

### Interactive render mode

Interactive Server (Interactive server-side rendering (interactive SSR) using Blazor Server)

### Steps To Reproduce

无

### Exceptions (if any)

_No response_

### .NET Version

NET9.0

### Anything else?

_No response_