fix(ci): disable lockdown mode in agentic workflow

[DimaBir]

Summary

• Disable lockdown: true in the gh-aw issue assistant workflow
• The microsoft org blocks SSO authorization for personal classic PATs, making lockdown mode unusable
• With lockdown: false, the workflow uses the built-in GITHUB_TOKEN which already has org access
• Security is still enforced via safe-outputs (comment limits, allowed labels, allowed domains)

Root cause

The agentic workflow was deployed with lockdown: true, which requires a custom GH_AW_GITHUB_TOKEN secret. However:

1. Fine-grained PATs can't scope to org repos you don't own
2. Classic PATs from personal accounts can't be SSO-authorized for the microsoft org

Test plan

• Re-run the workflow on issue Test issue for GHCP Agentic Workflow autoresolve - dbirenbaum #166 to verify it can read issue data and post comments