Delete router test - API scenario

Test tries to delete router, up untill the last is finally deleted.
"Conflict Errors" are covered for each router's "in use" port.

Note: this patch removes "old test" in:
neutron_tempest_plugin/api/test_routers_negative.py L:44
because this test is actually removes router when it has no dependencies
and it's not about the "Error" validation only.

Change-Id: I45629e89ca357306c3fad607647eb30baedfec04
2 files changed