Fix tests for snapshots extended_snapshot_attributes policy

This fixes the Patrole test for
"volume_extension:extended_snapshot_attributes" which is
incorrectly being executed by a create test which is wrong according
to [0]. Instead, the test should be executed for
GET /snapshots/{snapshot_id} and GET /snapshots/details. Further, the
test should use soft or non-fatal authorization, which was recently
fixed in Cinder [1].

Finally, the tests should live in test_volumes_snapshots_rbac
for the same reason the policy is listed under snapshots family
of policies in cinder [0].

The expected attributes for these tests can be found here: [2].

[0] https://github.com/openstack/cinder/blob/831665f59a0d87f2dbf7fa4f7496305977a98b0f/cinder/policies/snapshots.py#L48
[1] https://review.openstack.org/#/c/553657/1
[2] https://github.com/openstack/cinder/blob/831665f59a0d87f2dbf7fa4f7496305977a98b0f/cinder/api/contrib/extended_snapshot_attributes.py#L25

Change-Id: I7770148584e10a08b3e133b1793a1533f1728fc1
2 files changed