[BUG]: Mistral does not working

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## Describe the bug

A clear and concise description of what the bug is.

Mistral with bedrock ConverseStream does'nt work.

[Cloud Watch Logs]
```
{
"schemaType": "ModelInvocationLog",
"schemaVersion": "1.0",
"timestamp": "2024-11-25T04:34:01Z",
"accountId": "241231359358",
"identity": {
"arn": "arn:aws:sts::241231359358:assumed-role/BedrockChatStack-WebSocketHandlerRole4D6EDDA6-ZlWJRBDYLEUo/BedrockChatStack-WebSocketHandler7115E6CA-tvD32M5nnzNp"
},
"region": "us-east-1",
"requestId": "84c8f065-8358-4eee-9ca3-4c99b067753d",
"operation": "ConverseStream",
"modelId": "mistral.mistral-large-2402-v1:0",
"errorCode": "ValidationException"
}
```

## To Reproduce

Steps to reproduce the behavior:

1. enable `enableMistral` in cdk.json
2. deploy cdk
3. select model with mistral
4. say hello in chat.

## Screenshots

If applicable, add screenshots to help explain your problem.

## Additional context

Add any other context about the problem here.

Start with cdk.json and the deployment/model-selection path described in the reproduction steps; enable enableMistral and reproduce the failure while checking the provided CloudWatch ConverseStream log. Trace the ValidationException for mistral.mistral-large-2402-v1:0, and consider the issue done when selecting Mistral and sending a chat message produces a working streamed response.

Written by the indexing model from the issue text.