cb-cmds: inconsistent way of handling embedded containers
If empty list of pools is passed to remote-subnet4-set then it causes deleting all pools in given subnet. If empty list of subnets is passed to remote-network4-set then nothing happens, it does not cause deleting subnets in the shared network.
This is inconsistent and unintuitive. Users will have problems with that. Explaining this in docs is not a fix for this issue.