l3cfg: drop NM_L3_CFG_COMMIT_TYPE_ASSUME and assume_config_once
ASSUME is causing more troubles than benefits it provides. This patch is dropping NM_L3_CFG_COMMIT_TYPE_ASSUME and assume_config_once. NM3LCfg will commit as if the sys-iface-state is MANAGED.
This patch is part of the effort to remove ASSUME from NetworkManager.