Refactor ember-concurrency task from generator to async/await syntax

[wozny1989]

Why This Change

• Modern syntax - async/await is more readable and maintainable than generators
• Better error handling - async/await provides cleaner error handling patterns
• Consistent with modern JavaScript - aligns with current best practices
• Simplified testing - no need for @waitfor decorator with async/await

Impact

• ✅ No functional changes - version checking behavior remains identical
• ✅ Tests still pass - async/await works seamlessly with ember-concurrency
• ✅ Cleaner code - more readable and maintainable
• ✅ Reduced dependencies - removed unnecessary @ember/test-waiters