Function create_multi_profile_device_settings 

pub fn create_multi_profile_device_settings() -> Result<DeviceSettings>

Create a DeviceSettings instance with multiple profiles for cache write-back testing

This creates a configuration with:

• memory profile (speed 1) - fast cache
• dashmap profile (speed 100) - slow persistent storage

This is useful for testing cache write-back behavior where data loaded from the slow backend should be cached to the fast backend.