When only using cyclic reads there is a subscription enabled without any items, and publish requests timeout without data as result

[marcschier]

Subs should only be enabled if there is 1 or more "reporting" monitored item in the subscription. Otherwise it should stay disabled:

[23-12-13 17:09:00.4498] info: Azure.IIoT.OpcUa.Publisher.Stack.Services.OpcUaSubscription[0]
      Now monitoring 160 nodes in subscription opc.tcp://:49320_3B45F154_<<UnknownWriterGroup>>:<<UnknownDataSet>>_($a5f4fde1e3afaa49ea70ad81fe864fd20af93f8c):13.
[23-12-13 17:09:00.4543] info: Azure.IIoT.OpcUa.Publisher.Stack.Services.OpcUaSubscription[0]
      **Enabled** Subscription opc.tcp://:49320_3B45F154_<<UnknownWriterGroup>>:<<UnknownDataSet>>_($a5f4fde1e3afaa49ea70ad81fe864fd20af93f8c):13 in session opc.tcp://10.207.250.132:49320_3B45F154_<<UnknownWriterGroup>>.
[23-12-13 17:09:30.4619] info: Azure.IIoT.OpcUa.Publisher.Services.PublisherDiagnosticCollector[0]
      Tracking diagnostics for <<UnknownWriterGroup>> was (re-)started.
[23-12-13 17:09:30.4620] info: Azure.IIoT.OpcUa.Publisher.Services.NetworkMessageSink[0]
      Started data flow with message from subscription <<UnknownDataSet>>_($a5f4fde1e3afaa49ea70ad81fe864fd20af93f8c) on opc.tcp://:49320/.

with sporadic

[23-12-13 17:20:00.4447] fail: Azure.IIoT.OpcUa.Publisher.Stack.Services.OpcUaStack[0]
      PUBLISH #4 - Unhandled error BadTimeout during Publish.
      Opc.Ua.ServiceResultException: BadTimeout
         at Opc.Ua.ClientBase.ValidateResponse(ResponseHeader header)
         at Opc.Ua.SessionClient.EndPublish(IAsyncResult result, UInt32& subscriptionId, UInt32Collection& availableSequenceNumbers, Boolean& moreNotifications, NotificationMessage& notificationMessage, StatusCodeCollection& results, DiagnosticInfoCollection& diagnosticInfos)
         at Opc.Ua.Client.Session.OnPublishComplete(IAsyncResult result)