[ADMIN_API]: Fix failover race condition

If the device delete happened before the rebuild the rebuild would send an
empty configuration to the new device.

This is because the link between the new device and logical load balancer has
not been committed yet.  So when the gearman thread tries to query the DB for
the logical load balancers it will get none back if the old device is gone.

Fix is to commit before we send it off to gearman

Change-Id: I83081510bc4458b26da64b572fc16077d518bcad