LiveTextConversationAsync fails due to Cannot extract voices from a non-audio request.

#### Steps to reproduce

1. https://github.com/googleapis/java-genai/pull/802
2. `mvn compile exec:java -Dexec.mainClass="com.google.genai.examples.LiveTextConversationAsync"`

```
[INFO] --- exec:3.5.0:java (default-cli) @ google-genai-examples ---
Using Gemini Developer API
SLF4J(W): No SLF4J providers were found.
SLF4J(W): Defaulting to no-operation (NOP) logger implementation
SLF4J(W): See https://www.slf4j.org/codes.html#noProviders for further details.
Live session closed with code: 1007 and reason: Cannot extract voices from a non-audio request.
An error occurred: com.google.genai.errors.GenAiIOException: WebSocket closed unexpectedly: Cannot extract voices from a non-audio request.
java.util.concurrent.ExecutionException: com.google.genai.errors.GenAiIOException: WebSocket closed unexpectedly: Cannot extract voices from a non-audio request.
at java.base/java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:396)
at java.base/java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2073)
at com.google.genai.examples.LiveTextConversationAsync.main(LiveTextConversationAsync.java:99)
at org.codehaus.mojo.exec.ExecJavaMojo.doMain(ExecJavaMojo.java:375)
at org.codehaus.mojo.exec.ExecJavaMojo.doExec(ExecJavaMojo.java:364)
at org.codehaus.mojo.exec.ExecJavaMojo.lambda$execute$0(ExecJavaMojo.java:286)
at java.base/java.lang.Thread.run(Thread.java:1583)
Caused by: com.google.genai.errors.GenAiIOException: WebSocket closed unexpectedly: Cannot extract voices from a non-audio request.
at com.google.genai.AsyncLive$GenAiWebSocketClient.onClose(AsyncLive.java:255)
at org.java_websocket.client.WebSocketClient.onWebsocketClose(WebSocketClient.java:688)
at org.java_websocket.WebSocketImpl.closeConnection(WebSocketImpl.java:557)
at org.java_websocket.WebSocketImpl.eot(WebSocketImpl.java:612)
at org.java_websocket.client.WebSocketClient.run(WebSocketClient.java:546)
... 1 more
```

Based on https://ai.google.dev/gemini-api/docs/live, it looks like it may be intentional that this used to but now no longer works?

If that is the case, and this is not just a temporary situation which is intended to be made working again in the future, then the [`LiveTextConversationAsync`](https://github.com/googleapis/java-genai/blob/8f2d67de9e74094635996ea204d86e225c71593b/examples/src/main/java/com/google/genai/examples/LiveTextConversationAsync.java#L87) and related currently broken examples should perhaps be removed?