Remove deprecated custom policy file options

This PS removes deprecated custom policy file options, including:

  * cinder_policy_file
  * glance_policy_file
  * keystone_policy_file
  * neutron_policy_file
  * nova_policy_file

Specifying the location of a custom policy file should instead be
done by setting ``[patrole] custom_policy_files`` instead, as it
works with any service name.

Change-Id: I7d5cfa8d3cbd8a3818553ea1066005f9315f100c
diff --git a/patrole_tempest_plugin/policy_authority.py b/patrole_tempest_plugin/policy_authority.py
index 0a1aa13..3f4236b 100644
--- a/patrole_tempest_plugin/policy_authority.py
+++ b/patrole_tempest_plugin/policy_authority.py
@@ -107,12 +107,10 @@
 
         # Prioritize dynamically searching for policy files over relying on
         # deprecated service-specific policy file locations.
+        self.path = None
         if CONF.patrole.custom_policy_files:
             self.discover_policy_files()
             self.path = self.policy_files.get(service)
-        else:
-            self.path = getattr(CONF.patrole, '%s_policy_file' % str(service),
-                                None)
 
         self.rules = policy.Rules.load(self._get_policy_data(service),
                                        'default')