bond,team: first disconnect slaves and then master
Created by: bengal
Some tests do this:
* Disconnect device "nm-bond"
* Bring "down" connection "bond0.0"
* Bring "down" connection "bond0.1"
When the master gets disconnected it also disconnects slaves, and so the other two steps are no-ops.
In some tests we then check that slaves don't auto-activate, but this can only work if the slaves are explicitly disconnected (which doesn't happen right now because step 2 and 3 have no effect).