fix copying level db files during commi

fix https://github.com/seaweedfs/seaweedfs/issues/4635

weed/storage/volume.go

@@ -92,7 +92,7 @@ func (v *Volume) IndexFileName() (fileName string) {
 
 func (v *Volume) FileName(ext string) (fileName string) {
 	switch ext {
-	case ".idx", ".cpx", ".ldb":
+	case ".idx", ".cpx", ".ldb", ".cpldb":
 		return VolumeFileName(v.dirIdx, v.Collection, int(v.Id)) + ext
 	}
 	// .dat, .cpd, .vif