feat(core): reorder processing 🙀

- fix quickcheck of add_back_markers()

For: #10516

core/src/ldml/ldml_markers.cpp

@@ -61,6 +61,7 @@ bool normalize_nfd(std::u16string &str) {
 void add_back_markers(std::u32string &str, const std::u32string &src, marker_map &map, marker_encoding encoding) {
   if (map.empty()) {
     // quick check, nothing to do if no markers
+    str = src;
     return;
   }
   // need to reconstitute.