CLOUDSTACK-985: Revert "Using different MAC for a pair of redundant routers"

The different MAC address for a pair of redundant router have issues when short
time network outrage happened. When this happened:

1. BACKUP(r-2) cannot receive the broadcast from MASTER(r-1).
2. Then r-2 would announce it's MASTER after 3 seconds, and send gratuitous ARP
to the gateway of public ip(usually a rack router).
3. The gateway of public ip would update it's ARP cache to associate the public
ip of the network to the MAC of r-2.
4. In the meantime, r-1 still sending out VRRP broadcast(due to network issue,
the broadcast never arrived at r-2), and acting as MASTER.
5. After network outrage, r-2 would receive the higher priority VRRP broadcast
from MASTER again, then receded as BACKUP.
6. But the public gateway would still associate public ip with MAC of r-2, thus
caused the issue. r-1 would no longer able to receive any packets from public
network.

And there is no way for r-1 to send gratuitous ARP again, because it's always
consider itself as MASTER, no state changed, and no hook existed for receiving
lower priority broadcast.

So I would revert this change, and introduce another commit to ensure the newly
create redundant router would share the same MAC as the first one.

This reverts commit 9f257aa60b62f24193bba3f7c902e7779632e01e.
CLOUDSTACK-985: Make sure RvR would always have same MAC address

Even with newly created RvR using "restartNetwork&cleanup=false" API.