enhance: produce DoPrepareEvent after finishing scheduling in all scaling groups#2181

fregataa wants to merge 20 commits intotopic/05-23-feature_sync_mismatch_between_db_and_agent_kernelslablup/backend.ai:topic/05-23-feature_sync_mismatch_between_db_and_agent_kernelsfrom

topic/05-26-enhance_produce_doprepareevent_after_finishing_scheduling_in_all_scaling_groupslablup/backend.ai:topic/05-26-enhance_produce_doprepareevent_after_finishing_scheduling_in_all_scaling_groupsCopy head branch name to clipboard