Problem: SCM sync at runtime on AAP projects clears local cache and breaks jobs if the SCM (e.g., GitLab) is in maintenance. Manually changing all projects is impractical.

Solution: Add a global AAP setting to temporarily disable all SCM project synchronizations, overriding individual project settings. Similar to existing "Enable Role/Collection Download" toggles.

Benefit: Prevents AAP job outages during SCM maintenance and simplifies administration by avoiding per-project changes.