[Bug]: The TOOL_CALL_RESULT event is being emitted for the backend tool

### Pre-flight Checklist

- [x] I have searched [existing issues](https://github.com/ag-ui-protocol/ag-ui/issues) and this hasn't been reported yet.
- [x] I am using the **latest** version AG-UI.

### Describe the Bug

I am using Google ADK integration with some backend tools (including skills etc)

I am noticing that the to the client application TOOL_CALL_XX events are being emitted for the backend tools also. For example ADK invoke list skills, read skill etc and the output of all that goes to the frontend.

I would think that in a pure server-client setup (say fastapi backend and react frontend), I would not like to send the response of tool calls in the backend to the frontend.

### Steps to Reproduce

Any simple ADK example with a tool should show this

### Expected Behavior

I am expecting the results of the backend tools should not be sent to the frontend.

### Environment

```text
ag-ui-adk>=0.7.0
```

### Screenshots

_No response_

### Logs & Errors

```shell

```

### Additional Context

_No response_