add configurable delta for skipping shards (#13967)

This PR is an attempt to make this configurable
as not all situations have same level of tolerable
delta, i.e disks are replaced days apart or even
hours.

There is also a possibility that nodes have drifted
in time, when NTP is not configured on the system.

cmd/erasure-healing-common.go

@@ -229,7 +229,6 @@ func disksWithAllParts(ctx context.Context, onlineDisks []StorageAPI, partsMetad
 	bucket, object string, scanMode madmin.HealScanMode) ([]StorageAPI, []error) {
 
 	var diskMTime time.Time
-	delta := 5 * time.Second
 	if !latestMeta.DataShardFixed() {
 		diskMTime = pickValidDiskTimeWithQuorum(partsMetadata,
 			latestMeta.Erasure.DataBlocks)
@@ -340,7 +339,7 @@ func disksWithAllParts(ctx context.Context, onlineDisks []StorageAPI, partsMetad
 		}
 
 		if !diskMTime.Equal(timeSentinel) && !diskMTime.IsZero() {
-			if !partsMetadata[i].AcceptableDelta(diskMTime, delta) {
+			if !partsMetadata[i].AcceptableDelta(diskMTime, shardDiskTimeDelta) {
 				// not with in acceptable delta, skip.
 				partsMetadata[i] = FileInfo{}
 				continue