bgpd: local routes use non-default distance

bgpd: local routes use non-default distance

Use user provided AD for local routes (aggregate).

 address-family ipv4 unicast
  distance bgp 20 200 210
  network 47.2.2.8/30
  aggregate-address 51.1.0.0/16

Testing Done:

Before aggr route uses default 200 AD even user provided local AD.
B>* 51.1.0.0/16 [200/0] unreachable (blackhole), weight 1, 00:01:14

After:
B>* 51.1.0.0/16 [210/0] unreachable (blackhole), weight 1, 00:00:01

Signed-off-by: Chirag Shah <chirag@nvidia.com>