[docker-frr]: Fix frr separated and unified configuration mode (#2962)

Author: lguohan

dockers/docker-fpm-frr/start.sh

@@ -8,9 +8,11 @@ if [ -z "$CONFIG_TYPE" ] || [ "$CONFIG_TYPE" == "separated" ]; then
     sonic-cfggen -d -y /etc/sonic/deployment_id_asn_map.yml -t /usr/share/sonic/templates/bgpd.conf.j2 > /etc/frr/bgpd.conf
     sonic-cfggen -d -t /usr/share/sonic/templates/zebra.conf.j2 > /etc/frr/zebra.conf
     touch /etc/frr/vtysh.conf
+    rm -f /etc/frr/frr.conf
 elif [ "$CONFIG_TYPE" == "unified" ]; then
     sonic-cfggen -d -y /etc/sonic/deployment_id_asn_map.yml -t /usr/share/sonic/templates/frr.conf.j2 >/etc/frr/frr.conf
     echo "service integrated-vtysh-config" > /etc/frr/vtysh.conf
+    rm -f /etc/frr/bgpd.conf /etc/frr/vtysh.conf
 fi
 
 sonic-cfggen -d -t /usr/share/sonic/templates/isolate.j2 > /usr/sbin/bgp-isolate
@@ -35,7 +37,7 @@ supervisorctl start zebra
 supervisorctl start staticd
 supervisorctl start bgpd
 
-if [ -z "$CONFIG_TYPE" ] || [ "$CONFIG_TYPE" == "separated" ]; then
+if [ "$CONFIG_TYPE" == "unified" ]; then
     supervisorctl start vtysh_b
 fi