Skip test_show_host volume test

This PS makes test_show_host volume test in test_volume_hosts_rbac
skip until bug 1732808 is resolved. This is because Cinder does
not currently do policy enforcement for this endpoint.

Instead, Cinder checks whether the request context is_admin [1].
The policy in code documentation [0] does not include the "show"
endpoint for the "volume_extension:hosts" policy action
(i.e. GET /hosts/{host_name} is missing).

[0] https://github.com/openstack/cinder/blob/10a3f4e1c6f21effc79fd309628111c221543e0d/cinder/policies/hosts.py
[1] https://github.com/openstack/cinder/blob/0cf910d4345c000e8c306b1cb2b2dd291975cf71/cinder/api/contrib/hosts.py#L149

Related-Bug: #1732808
Change-Id: I348166738ae574ebd7220802cfc00f143d52aa2c
diff --git a/patrole_tempest_plugin/tests/api/volume/test_volume_hosts_rbac.py b/patrole_tempest_plugin/tests/api/volume/test_volume_hosts_rbac.py
index 9519cea..726f84e 100644
--- a/patrole_tempest_plugin/tests/api/volume/test_volume_hosts_rbac.py
+++ b/patrole_tempest_plugin/tests/api/volume/test_volume_hosts_rbac.py
@@ -28,6 +28,7 @@
         self.rbac_utils.switch_role(self, toggle_rbac_role=True)
         self.volume_hosts_client.list_hosts()
 
+    @decorators.skip_because(bug="1732808")
     @decorators.idempotent_id('9ddf321e-788f-4787-b8cc-dfa59e264143')
     @rbac_rule_validation.action(service="cinder",
                                  rule="volume_extension:hosts")