[docker-frr]: change default routing mode to separated and fix a bug in separated mode (#2961)

In separated mode, frr requires to run vtysh_b to load individual configuration

Signed-off-by: Guohan Lu <gulv@microsoft.com>

dockers/docker-fpm-frr/start.sh

@@ -35,7 +35,7 @@ supervisorctl start zebra
 supervisorctl start staticd
 supervisorctl start bgpd
 
-if [ "$CONFIG_TYPE" == "unified" ]; then
+if [ -z "$CONFIG_TYPE" ] || [ "$CONFIG_TYPE" == "separated" ]; then
     supervisorctl start vtysh_b
 fi
 

src/sonic-config-engine/minigraph.py

@@ -432,7 +432,7 @@ def parse_xml(filename, platform=None, port_config_file=None):
     neighbors = None
     devices = None
     hostname = None
-    docker_routing_config_mode = "unified"
+    docker_routing_config_mode = "separated"
     port_speeds_default = {}
     port_speed_png = {}
     port_descriptions = {}