Since NVP advanced services(LB/FW/VPN) are all routed inserted,
it is necessary to check service in use before deleting a router.
*If there is one service inserted into the router, it would raise
RouterInUseByXXService error when deleting the router.
Change-Id: I9844f53918cad17cafde0783fe6b69cff246791d
Close-Bug: #1295494