Remove duplicate test_unmanage_volume test

This patchset removes the duplicate test_umanage_volume test
from test_volume_actions_rbac [0] because it is more appropriate
to keep it in test_volumes_manage_rbac [1]. Besides the latter
implementation is more robust.

[0] https://github.com/openstack/patrole/blob/1f2ba24f4df09ba3711aa520bdf1bedb63e7797a/patrole_tempest_plugin/tests/api/volume/test_volume_actions_rbac.py#L147
[1] https://github.com/openstack/patrole/blob/7676a21077b5d8078f5beb32f7186970f02fc1a1/patrole_tempest_plugin/tests/api/volume/test_volumes_manage_rbac.py#L113

Change-Id: I96705df2cfaf9e0885e53de15675581508dd7c3c
diff --git a/patrole_tempest_plugin/tests/api/volume/test_volume_actions_rbac.py b/patrole_tempest_plugin/tests/api/volume/test_volume_actions_rbac.py
index 46f7a3e..d69f1e9 100644
--- a/patrole_tempest_plugin/tests/api/volume/test_volume_actions_rbac.py
+++ b/patrole_tempest_plugin/tests/api/volume/test_volume_actions_rbac.py
@@ -140,16 +140,6 @@
         self.addCleanup(self.volumes_client.update_volume_readonly,
                         self.volume['id'], readonly=False)
 
-    @decorators.idempotent_id('72bab13c-dfaf-4b6d-a132-c83a85fb1776')
-    @rbac_rule_validation.action(
-        service="cinder",
-        rule="volume_extension:volume_unmanage")
-    def test_unmanage_volume(self):
-        volume = self.create_volume()
-
-        with self.rbac_utils.override_role(self):
-            self.volumes_client.unmanage_volume(volume['id'])
-
     @decorators.idempotent_id('59b783c0-f4ef-430c-8a90-1bad97d4ec5c')
     @rbac_rule_validation.action(service="cinder",
                                  rule="volume:update")