fix retry for already finished read

fixes #19182

Author: gridnevvvit

ydb/core/kqp/runtime/kqp_stream_lookup_actor.cpp

@@ -540,7 +540,11 @@ class TKqpStreamLookupActor : public NActors::TActorBootstrapped<TKqpStreamLooku
 
     void Handle(TEvPrivate::TEvRetryRead::TPtr& ev) {
         auto readIt = Reads.find(ev->Get()->ReadId);
-        YQL_ENSURE(readIt != Reads.end(), "Unexpected readId: " << ev->Get()->ReadId);
+        if (readIt == Reads.end()) {
+            CA_LOG_D("received retry request for already finished/non-existing read, read_id: " << ev->Get()->ReadId);
+            return;
+        }
+
         auto& read = readIt->second;
 
         YQL_ENSURE(read.State != EReadState::Blocked || read.LastSeqNo <= ev->Get()->LastSeqNo);