Add missing default policy files for debian-binary-horizon

The debian-binary-horizon image is missing the default policies files
which should be in /etc/openstack-dashboard/default_policies. By copying
everything from /etc/openstack-dashboard/policy
into /etc/openstack-dashboard, we get the default policy files, as well
as commented out policy files (e.g. cinder_policy.yaml) and the
nova_policy.d directory containing api-extensions.yaml.

Change was merged for ubuntu in [1] but unfortunatelly
not for debian, this trivial patch fixes it also
for debian.

[1] https://review.opendev.org/c/openstack/kolla/+/794589

Closes-Bug: #1933759
Change-Id: I822d640a251e6ed9f71c76a922513e23e4218418

docker/horizon/Dockerfile.j2

@@ -83,7 +83,7 @@ RUN sed -i 's|\(ServerTokens \)OS|\1Prod|' /etc/apache2/conf-available/security.
     && cp -r /usr/share/openstack-dashboard/openstack_dashboard/conf/* /etc/openstack-dashboard \
     && rm /etc/apache2/conf-enabled/openstack-dashboard.conf \
     {% else %}
-    && cp /etc/openstack-dashboard/policy/*.json /etc/openstack-dashboard \
+    && cp -r /etc/openstack-dashboard/policy/* /etc/openstack-dashboard \
     {% endif %}
     && cp /usr/share/openstack-dashboard/manage.py /usr/bin/manage.py \
     && rm /etc/openstack-dashboard/local_settings.py \

releasenotes/notes/bug-1933759-c03e50c243850a49.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fix missing default policy files for debian-binary-horizon.
+    `LP#1933759 <https://launchpad.net/bugs/1933759>`__