fix: incorrect root path in API client requests (#6136)

#### What type of PR is this?

/area ui
/kind bug

#### What this PR does / why we need it:

修复 api client 默认请求根地址不正确的问题。

#### Does this PR introduce a user-facing change?

```release-note
None
```

ui/packages/api-client/entry/api-client.ts

@@ -68,6 +68,7 @@ import {
 } from "../src";
 
 const defaultAxiosInstance = axios.create({
+  baseURL: "/",
   withCredentials: true,
 });