fix(gateway): carry _db_persisted stamp in _build_replay_entry to prevent duplicate transcript flushes (#123462)

(cherry picked from commit 7366ba26e91907641527d698a72f0f57de530eba)

gateway/run.py

@@ -1148,6 +1148,8 @@ def _build_replay_entry(
             entry[_rkey] = _rval
     if preserve_timestamp and msg.get("timestamp"):
         entry["timestamp"] = msg["timestamp"]
+    if msg.get("_db_persisted"):
+        entry["_db_persisted"] = True
     return entry