GitLab Duo: AI-powered CI/CD pipeline root cause analysis

Introduces GitLab Duo Root Cause Analysis, an AI-powered feature that analyzes CI/CD job logs to identify the root cause of pipeline failures and suggest fixes. Details the mechanism of forwarding logs to the GitLab AI Gateway for LLM analysis and provides two detailed examples: diagnosing Python dependency errors (ModuleNotFoundError) and missing Go runtimes in containerized environments. Demonstrates how to fix these issues by modifying `.gitlab-ci.yml` and Dockerfiles, and suggests using GitLab Duo Chat for follow-up questions and advanced troubleshooting.