When a global checkpoint is created (one with empty device list) we
save the status of all devices to restore it later. After the
checkpoint new interfaces and connections may appear and they can
significantly influence the overall networking status, but we don't
consider them at the moment.

Introduce a new flag DELETE_NEW_CONNECTIONS to delete any connection
added after the checkpoint and similarly a DISCONNECT_NEW_DEVICES to
ensure that the connection active on newly appeared devices doesn't
disrupt network connectivity.

https://bugzilla.redhat.com/show_bug.cgi?id=1378393