### Check for existing issues

- [x] I have searched the existing issues and checked that my issue is not a duplicate.

### What happened?

I am encountering an issue where message contents (prompts and completions) are completely missing from traces when using the OpenTelemetry V2 integration.

*(Note: This might be related to #30121, which reports missing messages for Anthropic routes. However, this seems to occur globally across providers when using V2).*

### Steps to Reproduce

To isolate the issue and rule out any OTLP collector/backend limitations, I am using the `console` exporter. I also explicitly omitted `"otel"` from my `config.yaml` callbacks to avoid running V1 and V2 simultaneously.

1. Start the proxy using the official docker container image (v1.89.2) with the following environment variables: ```yaml LITELLM_OTEL_V2: "true" OTEL_EXPORTER: "console" OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT: "span_and_event"

```

2. Send a standard chat completion request to the proxy. 3. Observe the output in the console.

### Expected Behavior Based on the documentation, the console output should include the message contents either as `gen_ai.input.messages` and `gen_a…