Gemport is not cleared on BAL if ofagent restarts when no subscriber is configured on the ONU for ATT workflow

Gemport is not cleared on BAL if ofagent restarts when no subscriber is configured on the ONU for ATT workflow.

When the Ofagent restarts all uni ports are disabled at ONOS. When uni port is disabled, EAPoL flow is removed. EAPoL being the only flow for the subscriber initially, and adapter detects that no flow is referencing the gemport and tcont, it initiates Queue and Scheduler removal.

There are no downstream Queues and Schedulers initially because EAPoL is upstream only flow. Since we are cleaning up bi-directional gemports only when downstream RemoveQueue was getting invoked in openolt agent application currently, the gemports continue to be uncleared on the BAL in this scenario.

It makes sense to delete the gemports when upstream RemoveQueue is getting called given this scenario and also the guarantee that upstream queues must exist always for a subscriber.

It is to be noted that in case of Multicast, the gem ports are downstream only so there could be an argument that this gemport is not cleared when RemoveQueue is getting invoked for downstream direction. This is currently OK because for multicast case the openolt agent application does not manage the creation and deletion of gemport but BAL does it for us.