engine: Don't resurrect removed bonds for label

If a network was attached via label to a bond being removed, the
operation would still be blocked by the CanDoAction, this is now
fixed.

Change-Id: Ie5c0648999a80c313f6565673e7880a2b34f3e53
Bug-Url: https://bugzilla.redhat.com/1084771
Bug-Url: https://bugzilla.redhat.com/1084915
Signed-off-by: Lior Vernia <lvernia@redhat.com>
(cherry picked from commit 433fa09c87eb88d6d5e187f25d7a2dd1e9cb4c35)