🔒 Cleanup repository secrets during trial runs

[dsyme]

Summary

• Improved secret cleanup mechanism in trial repository workflow
• Modified secret removal strategy to include GH_AW_GITHUB_TOKEN
• Implemented defer-based secret cleanup to ensure cleanup always occurs

Key Changes

• Updated cleanupTrialSecrets() to remove GH_AW_GITHUB_TOKEN alongside other API keys
• Added deferred secret cleanup in RunWorkflowTrials() to guarantee cleanup
• Simplified merge and update workflow logic in update command
• Cleaned up documentation for workflow update process