Fix for null ref exception in Service Bus scale-out:
- The ConnectionContext is now created immediately and passed in to the Subscribe call for initialization, so it should never be null
- #2933
Fixes null ref errors in Service Bus scale-out:
- Handle when the factory creation fails in the ServiceBusConnection ctor
- Handle when topics are never created and then are attempted to be closed in Dispose
- #2937
Merge branch 'release' into dev