Clarify ADK + LiteLLM integration to prevent duplicate trace confusion

## Problem
Users are experiencing duplicate traces when using ADK + LiteLLM integration, causing confusion about proper setup.

## Files to Update
- docs/v2/examples/google_adk.mdx
- docs/v2/integrations/google_adk.mdx

## Changes Needed
- Document how AgentOps ADK instrumentor prevents duplicate spans
- Add troubleshooting section for duplicate trace issues
- Clarify proper setup patterns to avoid duplicates
- Explain the relationship between ADK's telemetry and AgentOps instrumentation

## Context
The ADK instrumentor specifically disables ADK's built-in telemetry to prevent duplicates, but this isn't clearly documented for users.

## Assignee
Please assign to Dwij when creating