Back port bug fixes in openonu go master to 2.8 branch

Back port bug fixes in openonu go master to 2.8 branch.

Here is the information provided by Michael Pagenkopf

Here is a list of completed R2.9 (master) stories, that still could be considered for R2.8 maintenance activities - together with the author and some remark. I did not include the GRPC related (which sometimes also relate to reconcile adaptations) or R2.9 feature extension stories. From all the stories listed here of course also only a subset could be considered - depending on the maintenance focus in R2.8 (e.g. for reconciling/OnuUpgrade/Multi-flow/Multi-Uni support):
VOL-4277 onu-adapter should change device's operational-state to FAILED if EnableDevice fails in adapter (Mahir)
VOL-4438 OnuDown indication can collide with FlowDeletion resulting in wrong flowDelete error indication (Michael)
VOL-4452 openonuAdapterGo - delete requests for objects of an already deleted ONU should be acknowledged positively (Holger)
VOL-4450 ONU upgrade to multiple ONU devices control insufficient, possibly leads to adapter crash (Michael)
VOL-4459 ONU connection state may be wrong or misleading after ONU soft reboot (Michael)
VOL-4474 I have converted CIR and PIR values to Bps. Openolt adapter sends it as kbps to openonu adapter (Ozge)
VOL-4469 Onu adapter reconcilement may stuck on VLAN processing, especially in TT traffic scenarios (Michael) (the part for reconcilement multi-flows per port)
Extension for OnuAdapter reconcilement on VLAN processing for Multi-UNI support (Michael) (if multi-UNI support at reconcilement is regarded as relevant)
VOL-4487 openonuAdapterGo - reconciling not working after ONU device disable (Holger) (if reconcile changes generally are relevant)
VOL-4492 sporadic issue ensuring the expected device reason (mib state) in Multi-UNI/Multi-ONU deployments (Michael) (if multi-UNI support is relevant)
VOL-4472 BBSim receives two "EndSoftwareDownloadRequest" when you abort the download (Michael)