[Bug] [dashboard] Add exclude node not work

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

### Search before asking

- [X] I have searched in the [issues](https://github.com/apache/incubator-uniffle/issues?q=is%3Aissue) and found no similar issues.

### Describe the bug

There are not `requestServerType` and `targetAddress` in headers.

### Affects Version(s)

master

### Uniffle Server Log Output

```logtalk
`dashboard.log`

[2024-08-02 10:00:27.002] [DashboardServer-47] [WARN] ServletHandler - /api/server/addExcludeNodes
java.lang.IllegalArgumentException: Invalid URI host: null (authority: null)
at org.eclipse.jetty.client.HttpClient.checkHost(HttpClient.java:487)
at org.eclipse.jetty.client.HttpClient.newHttpRequest(HttpClient.java:472)
at org.eclipse.jetty.client.HttpClient.newRequest(HttpClient.java:430)
at org.eclipse.jetty.client.HttpClient.newRequest(HttpClient.java:419)
at org.eclipse.jetty.proxy.ProxyServlet.service(ProxyServlet.java:80)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:848)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:584)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1180)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:512)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1112)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:52)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:134)
at org.eclipse.jetty.server.Server.handle(Server.java:539)
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:333)
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:251)
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:283)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:108)
at org.eclipse.jetty.io.SelectChannelEndPoint$2.run(SelectChannelEndPoint.java:93)
at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.executeProduceConsume(ExecuteProduceConsume.java:303)
at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.produceConsume(ExecuteProduceConsume.java:148)
at org.eclipse.jetty.util.thread.strategy.ExecuteProduceConsume.run(ExecuteProduceConsume.java:136)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:833)
```
```

### Uniffle Engine Log Output

_No response_

### Uniffle Server Configurations

_No response_

### Uniffle Engine Configurations

_No response_

### Additional context

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

Start by tracing the dashboard `/api/server/addExcludeNodes` entry point and the request path that reaches Jetty's `ProxyServlet`; inspect how the request headers are assembled. Reproduce the request and verify that `requestServerType` and `targetAddress` are present and that the `Invalid URI host: null` error no longer occurs.

Written by the indexing model from the issue text.