change level logging on delete session debug

Author: KirillKurdyukov

src/Ydb.Sdk/src/Ado/Session/PoolingSession.cs

@@ -235,7 +235,7 @@ internal override async Task DeleteSession()
         }
         catch (Exception e)
         {
-            _logger.LogWarning(e, "Error occurred while deleting session[{SessionId}] (NodeId = {NodeId})",
+            _logger.LogDebug(e, "Error occurred while deleting session[{SessionId}] (NodeId = {NodeId})",
                 SessionId, NodeId);
         }
     }