volume: file counter should be all files

address https://github.com/seaweedfs/seaweedfs/pull/3388#issuecomment-1220466228

weed/storage/needle_map_metric.go

@@ -105,9 +105,8 @@ func newNeedleMapMetricFromIndexFile(r *os.File) (mm *mapMetric, err error) {
 			mm.FileByteCounter += uint64(size)
 		}
 
-		if !bf.TestAndAdd(buf) {
-			mm.FileCounter++
-		} else {
+		mm.FileCounter++
+		if bf.TestAndAdd(buf) {
 			// deleted file
 			mm.DeletionCounter++
 			if size.IsValid() {