What I did:
Following changes done for packet based chassis:-
1> Run arp_update on LC's to resolve static route nexthops over backend
port-channel interfaces.
2> On Supervisor make sure arp_update exit gracefully
#### Why I did it
* `arp_update` fails to ping those neighbors over vlan sub interfaces.
#### How I did it
* modify `arp_update_vars.j2` to get vlan sub interfaces with ipv6 addresses assigned.
* modify `arp_update` to send ipv6 pings over those retrieved vlan sub interfaces.
Signed-off-by: Longxiang Lyu <lolv@microsoft.com>
This PR limited the number of calls to sonic-cfggen to one call
per iteration instead of current 3 calls per iteration.
The PR also installs jq on host for future scripts if needed.
signed-off-by: Tamer Ahmed <tamer.ahmed@microsoft.com>
