Fix fast distributed checkpoint loading

[jlamypoirier]

✨ Description

Distributed checkpoint loading failed because workers disagreed on the loading method. Fix that, make checkpoint loading a bit less verbose, and add some safety barriers.

🔍 Type of change

Select all that apply:

• [x] 🐛 Bug fix (non-breaking change that addresses a specific issue)
• [ ] 🚀 New feature (non-breaking change that adds functionality)
• [ ] ⚠️ Breaking change (a change that could affect existing functionality)
• [ ] 📈 Performance improvement/optimization (improves speed, memory usage, or efficiency)
• [ ] 🛠️ Code refactor (non-functional changes that improve code readability, structure, etc.)
• [ ] 📦 Dependency bump (updates dependencies, including Dockerfile or package changes)
• [ ] 📝 Documentation change (updates documentation, including new content or typo fixes)
• [ ] 🔧 Infrastructure/Build change (affects build process, CI/CD, or dependencies)