[swss] Start Arp Update Process (#5391)

Arp update process was not being started due to an issue with
the directory name having an extra 'd' in supervisor as in
'/etc/supervisord/conf.d/arp_update.conf'.

signed-off-by: Tamer Ahmed <tamer.ahmed@microsoft.com>

dockers/docker-orchagent/docker-init.sh

@@ -15,7 +15,7 @@ fi
 # Start arp_update when VLAN exists
 VLAN=`sonic-cfggen -d -v 'VLAN.keys() | join(" ") if VLAN'`
 if [ "$VLAN" != "" ]; then
-    cp /usr/share/sonic/templates/arp_update.conf /etc/supervisord/conf.d/
+    cp /usr/share/sonic/templates/arp_update.conf /etc/supervisor/conf.d/
 fi
 
 exec /usr/bin/supervisord