Stale flows in fib table after dissociating router from VPN

Issue:

Flows corresponding to routes from dc-gw are not removed from one DPN after dissociating router from DPN.

Test Case:

Configure 8 dualstack networks, 2 VMs in each network connected to one compute each.

Configure 2 routers, associate 4 networks to each router.

Configure 2 VPNs with 4 RDs each. Associate one router to one VPN each.

Configure extra routes and unconfigure.

Dissociate router2 from VPN2.

Expectation: Routes from DC-GW to be withdrawn from ODL FIB and flows for that routes to be cleaned up from computes.

Actual result: Routes are withdrawn from ODL FIB. Flows didnt get removed from one DPN