[test_mux] add sleep in test_NH (#2648)

* [test_mux] add sleep in test_NH

What I did: added sleep after adding/removing neighbors in test_NH

Why I did it: resolve PR failures due to timing issues between
adding/deleting neighbors and them being present in the asic_db

Signed-off-by: Nikola Dancejic <ndancejic@microsoft.com>

tests/test_mux.py

@@ -560,6 +560,8 @@ def create_and_test_NH_routes(self, appdb, asicdb, dvs, dvs_route, mac):
             " " + neigh_ipv6 + "\""
         )
         apdb.wait_for_entry("ROUTE_TABLE", nh_route)
+        apdb.wait_for_entry("ROUTE_TABLE", nh_route_ipv6)
+
         rtkeys = dvs_route.check_asicdb_route_entries([nh_route])
         rtkeys_ipv6 = dvs_route.check_asicdb_route_entries([nh_route_ipv6])
         self.check_nexthop_in_asic_db(asicdb, rtkeys[0])
@@ -572,16 +574,22 @@ def create_and_test_NH_routes(self, appdb, asicdb, dvs, dvs_route, mac):
 
         self.del_neighbor(dvs, neigh_ip)
         self.del_neighbor(dvs, neigh_ipv6)
+        apdb.wait_for_deleted_entry(self.APP_NEIGH_TABLE, neigh_ip)
+        apdb.wait_for_deleted_entry(self.APP_NEIGH_TABLE, neigh_ipv6)
+        asicdb.wait_for_deleted_entry(self.ASIC_NEIGH_TABLE, neigh_ip)
+        asicdb.wait_for_deleted_entry(self.ASIC_NEIGH_TABLE, neigh_ip)
+
         self.check_nexthop_in_asic_db(asicdb, rtkeys[0], True)
         self.check_nexthop_in_asic_db(asicdb, rtkeys_ipv6[0], True)
 
         # Set state to active, learn neighbor again
         self.set_mux_state(appdb, "Ethernet0", "active")
-        self.check_nexthop_in_asic_db(asicdb, rtkeys[0], True)
-        self.check_nexthop_in_asic_db(asicdb, rtkeys_ipv6[0], True)
 
         self.add_neighbor(dvs, neigh_ip, mac)
         self.add_neighbor(dvs, neigh_ipv6, mac)
+        self.check_neigh_in_asic_db(asicdb, neigh_ip)
+        self.check_neigh_in_asic_db(asicdb, neigh_ipv6)
+
         self.check_nexthop_in_asic_db(asicdb, rtkeys[0])
         self.check_nexthop_in_asic_db(asicdb, rtkeys_ipv6[0])
         dvs.runcmd(