Update severity calculation for VDisks inside PDisk space distribution

[artemmufazalov]

1. Rename Disk Distribution to Space Distribution
2. Colorize Log inside distribution with 85/95 size thresholds
3. Update severity calculation for VDisks inside space distribution (calculateVDiskSeverity function)
   3.1. Colorize VDisks inside distribution with 85/95 size thresholds
   3.2. Do not include PDisk status in VDisk severity calculation there is not PDiskStatus in VDisk severity calculation
   3.3. Do not change severity calculation inside Storage table