fix batch message deduplication logic to not update batch on already …

…batched message (#4789)

src/ServiceControl.Persistence.RavenDB/RetryDocumentDataStore.cs

@@ -113,7 +113,7 @@ static ICommandData CreateFailedMessageRetryDocument(string batchDocumentId, str
                 }
             };
 
-            return new PatchCommandData(FailedMessageRetry.MakeDocumentId(messageId), null, patch: patchRequest, patchIfMissing: patchRequest);
+            return new PatchCommandData(FailedMessageRetry.MakeDocumentId(messageId), null, patch: new PatchRequest { Script = "" }, patchIfMissing: patchRequest);
         }
 
         public async Task GetBatchesForAll(DateTime cutoff, Func<string, DateTime, Task> callback)