cinder can not use system scope due to endpoints including project

Description
===========
There are several scope type such as project-scope, domain-scope
and system-scope. Cinder cannot use system scope since its
endpoint has project_id and will get an empty url in catalog
in system scope.

Example
===========
root@devcon:~# openstack endpoint list
+----------------------------------+-----------+--------------+----------------+---------+-----------+-------------------------------------------------+
| ID | Region | Service Name | Service Type | Enabled | Interface | URL |
+----------------------------------+-----------+--------------+----------------+---------+-----------+-------------------------------------------------+
| 28e4c8be89924e02a17798c31ecb5d66 | RegionOne | neutron | network | True | public | http://192.168.32.130:9696/ |
| 3f57b61baaa34c649d8c8f60212d76b7 | RegionOne | cinder | block-storage | True | public | http://192.168.32.130/volume/v3/$(project_id)s |
| 45828996f0c74547b17edd16139a85b7 | RegionOne | nova_legacy | compute_legacy | True | public | http://192.168.32.130/compute/v2/$(project_id)s |
| 6aca49b3126a4b5f81621da20ec72b37 | RegionOne | cinderv3 | volumev3 | True | public | http://192.168.32.130/volume/v3/$(project_id)s |
| 8098612e886048e99d9325037c7b2009 | RegionOne | placement | placement | True | public | http://192.168.32.130/placement |
| 8bf8ffe569044d10b40e4ee1decfd087 | RegionOne | nova | compute | True | public | http://192.168.32.130/compute/v2.1 |
| ce646c265f924e5283a1a424270d1668 | RegionOne | keystone | identity | True | public | http://192.168.32.130/identity |
| d62be193ddb946518a7d3df0bcab3ea3 | RegionOne | glance | image | True | public | http://192.168.32.130/image |
| e6ac2695caca4bab883fa3fbc4b7b5bd | RegionOne | keystone | identity | True | admin | http://192.168.32.130/identity |
| e9b1c033578e40819bb6aad502697bb8 | RegionOne | cinderv2 | volumev2 | True | public | http://192.168.32.130/volume/v2/$(project_id)s |
+----------------------------------+-----------+--------------+----------------+---------+-----------+-------------------------------------------------+
root@devcon:/usr/local/lib/python3.6/dist-packages/keystoneauth1# openstack --os-auth-url="http://192.168.32.130/identity" --os-username=alice --os-user-domain-name=default --os-password=admin --os-system-scope all catalog list
+-------------+----------------+----------------------------------------------+
| Name | Type | Endpoints |
+-------------+----------------+----------------------------------------------+
| neutron | network | RegionOne |
| | | public: http://192.168.32.130:9696/ |
| | | |
| glance | image | RegionOne |
| | | public: http://192.168.32.130/image |
| | | |
| nova | compute | RegionOne |
| | | public: http://192.168.32.130/compute/v2.1 |
| | | |
| cinder | block-storage | |
| keystone | identity | RegionOne |
| | | public: http://192.168.32.130/identity |
| | | RegionOne |
| | | admin: http://192.168.32.130/identity |
| | | |
| nova_legacy | compute_legacy | |
| cinderv3 | volumev3 | |
| cinderv2 | volumev2 | |
| placement | placement | RegionOne |
| | | public: http://192.168.32.130/placement |
| | | |
+-------------+----------------+----------------------------------------------+