Run the data scanner routine in a loop (#13928)

After the introduction of Refresh logic in locks, the data scanner can
quit when the data scanner lock is not able to get refreshed. In that
case, the context of the data scanner will get canceled and
runDataScanner() will quit. Another server would pick the scanning
routine but after some time, all nodes can just have all scanning
routine aborted, as described above.

This fix will just run the data scanner in a loop.

cmd/data-scanner.go

@@ -71,7 +71,17 @@ var (
 
 // initDataScanner will start the scanner in the background.
 func initDataScanner(ctx context.Context, objAPI ObjectLayer) {
-	go runDataScanner(ctx, objAPI)
+	go func() {
+		// Run the data scanner in a loop
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+				runDataScanner(ctx, objAPI)
+			}
+		}
+	}()
 }
 
 type safeDuration struct {