[#725] writecache: Fix metric values

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/writecache/writecachebadger/delete.go

@@ -59,7 +59,7 @@ func (c *cache) Delete(ctx context.Context, addr oid.Address) error {
 					storagelog.OpField("db DELETE"),
 				)
 				deleted = true
-				c.objCounters.DecDB()
+				c.decDB()
 			}
 			return err
 		}