New "test_remove_associated_ports" negative test case

Test scenario:
1) Add external gateway to the existing router
2) Add interface to the existing router
3) List all ports associated with router
   There are 2 ports: one related to external gateway
   and the second one is related to created router interface
4) Try to delete routers's ports (should fail)

Change-Id: I62ff58aa0f08c2c158743237d0ca16ec6a9aa589
1 file changed