Fix InMemoryTransactionIdStorage stale session on reconnect

Get(persistable:true) used SafeAdd which returned the cached session
with old requestId mappings. When a client reconnects with the same
sessionId, CreateTransactionId throws "duplicated". Replace SafeAdd
with unconditional assignment to always create a fresh session.

Author: mikasoukhov

Configuration/ITransactionIdStorage.cs

@@ -142,7 +142,14 @@ bool ISessionTransactionIdStorage.RemoveTransactionId(long transactionId)
 	private readonly SynchronizedDictionary<string, ISessionTransactionIdStorage> _item = [];
 
 	ISessionTransactionIdStorage ITransactionIdStorage.Get(string sessionId, bool persistable)
-		=> persistable ? _item.SafeAdd(sessionId, key => new InMemorySessionTransactionIdStorage(_idGenerator)) : new InMemorySessionTransactionIdStorage(_idGenerator);
+	{
+		if (!persistable)
+			return new InMemorySessionTransactionIdStorage(_idGenerator);
+
+		var session = new InMemorySessionTransactionIdStorage(_idGenerator);
+		_item[sessionId] = session;
+		return session;
+	}
 }
 
 /// <summary>