Replace legacy SmartCache with MetricCollectionManager for granular control:
- RealTime tier (5s): CPU load, CPU temperature, Service CPU usage
- Fast tier (30s): Memory usage, top processes
- Medium tier (5min): Service status, C-states, users
- Slow tier (15min): Disk usage
All CPU-related metrics now update consistently every 5 seconds as requested,
eliminating the previous inconsistency where only CPU load was updating
at the correct frequency while service CPU usage was on 5-minute intervals.