Issue

• some api test fail because os_compute_api:os-assisted-volume-snapshots:create is admin-only.
  The affected tests are

  tempest.api.volume.test_volumes_snapshots.VolumesSnapshotTestJSON.test_snapshot_create_delete_with_volume_in_use
  tempest.api.volume.test_volumes_snapshots.VolumesSnapshotTestJSON.test_snapshot_create_offline_delete_online
  tempest.scenario.test_volume_boot_pattern.TestVolumeBootPattern.test_create_ebs_image_and_check_boot
  tempest.scenario.test_volume_boot_pattern.TestVolumeBootPattern.test_volume_boot_pattern
  

  cinder has following logs.

  ERROR cinder.volume.drivers.remotefs [req-XXX XXX XXX - default default] Call to Nova to create snapshot failed: Forbidden: Policy doesn't allow os_compute_api:os-assisted-volume-snapshots:create to be performed. (HTTP 403) (Request-ID: req-XXX)
  ERROR cinder.volume.drivers.remotefs Traceback (most recent call last):
  ERROR cinder.volume.drivers.remotefs   File "/usr/lib/python2.7/site-packages/cinder/volume/drivers/remotefs.py", line 1452, in _create_snapshot_online
  ERROR cinder.volume.drivers.remotefs     connection_info)
  ERROR cinder.volume.drivers.remotefs   File "/usr/lib/python2.7/site-packages/cinder/compute/nova.py", line 188, in create_volume_snapshot
  ERROR cinder.volume.drivers.remotefs     create_info=create_info)
  ERROR cinder.volume.drivers.remotefs   File "/usr/lib/python2.7/site-packages/novaclient/v2/assisted_volume_snapshots.py", line 43, in create
  ERROR cinder.volume.drivers.remotefs     return self._create('/os-assisted-volume-snapshots', body, 'snapshot')
  ERROR cinder.volume.drivers.remotefs   File "/usr/lib/python2.7/site-packages/novaclient/base.py", line 361, in _create
  ERROR cinder.volume.drivers.remotefs     resp, body = self.api.client.post(url, body=body)
  ERROR cinder.volume.drivers.remotefs   File "/usr/lib/python2.7/site-packages/keystoneauth1/adapter.py", line 310, in post
  ERROR cinder.volume.drivers.remotefs     return self.request(url, 'POST', **kwargs)
  ERROR cinder.volume.drivers.remotefs   File "/usr/lib/python2.7/site-packages/novaclient/client.py", line 83, in request
  ERROR cinder.volume.drivers.remotefs     raise exceptions.from_response(resp, body, url, method)
  ERROR cinder.volume.drivers.remotefs Forbidden: Policy doesn't allow os_compute_api:os-assisted-volume-snapshots:create to be performed. (HTTP 403) (Request-ID: req-XXX)