Remove policy file from nova-conductor config.json template

Change I810aad7d49db3f5a7fd9a2f0f746fd912fe03917 for supporting multiple
Nova cells updated the list of containers that require a policy file to
only include nova-api, nova-compute, and nova-compute-ironic.

The nova-conductor config.json template was left unchanged and fails to
copy the nova policy file into its container. This can be seen on a
fresh deployment, but might be missed on an upgrade if an older policy
file is still available in /etc/kolla/nova-conductor.

This commit removes the nova_policy_file block from the nova-conductor
config.json template, as it shouldn't be required.

Backport: ussuri, train
Change-Id: I17256b182d207aeba3f92c65a6d7cf3611180558
Closes-Bug: #1886170

ansible/roles/nova-cell/templates/nova-conductor.json.j2

@@ -6,13 +6,7 @@
             "dest": "/etc/nova/nova.conf",
             "owner": "nova",
             "perm": "0600"
-        }{% if nova_policy_file is defined %},
-        {
-            "source": "{{ container_config_directory }}/{{ nova_policy_file }}",
-            "dest": "/etc/nova/{{ nova_policy_file }}",
-            "owner": "nova",
-            "perm": "0600"
-        }{% endif %}
+        }
     ],
     "permissions": [
         {

releasenotes/notes/bug-1886170-f76d9d3520ab86ec.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixes an incorrect configuration for nova-conductor when a custom Nova
+    policy was applied, preventing the ``nova_conductor`` container from
+    starting successfully. `LP#1886170
+    <https://bugs.launchpad.net/kolla-ansible/+bug/1886170>`__