Read drive IO stats from sysfs instead of procfs (#19131)

Currently, we read from `/proc/diskstats` which is found to be
un-reliable in k8s environments. We can read from `sysfs` instead.

Also, cache the latest drive io stats to find the diff and update
the metrics.

internal/disk/disk.go

@@ -40,15 +40,6 @@ type Info struct {
 	NRRequests uint64
 }
 
-// DevID is the drive major and minor ids
-type DevID struct {
-	Major uint32
-	Minor uint32
-}
-
-// AllDrivesIOStats is map between drive devices and IO stats
-type AllDrivesIOStats map[DevID]IOStats
-
 // IOStats contains stats of a single drive
 type IOStats struct {
 	ReadIOs        uint64