systemd: Add missing clean for init sh script

scripts/remove

@@ -23,7 +23,7 @@ domain=$(sudo yunohost app setting vpnclient domain)
 # The End
 sudo systemctl stop ynh-vpnclient --quiet
 sudo yunohost service remove ynh-vpnclient
-sudo rm -f /lib/systemd/system/ynh-vpnclient.service
+sudo rm -f /lib/systemd/system/ynh-vpnclient.service /usr/local/bin/ynh-vpnclient
 sudo rm -f /tmp/.ynh-vpnclient-*
 
 # Remove confs