Improve Ironic Horizon out of the box experience

Policy override was causing lots of error messages in the Ironic view of
Horizon.

I've asked upstream if we can get this enabled by default:

https://bugs.launchpad.net/horizon/+bug/2102214

But are yet to see any traction.

Author: jovial

etc/kayobe/kolla/config/horizon/_9999-custom-settings.py

@@ -0,0 +1 @@
+SYSTEM_SCOPE_SERVICES = ['ironic']

etc/kayobe/kolla/config/ironic/policy.yaml

@@ -4,4 +4,4 @@
 # GET  /nodes/detail
 # Intended scope(s): system, project
 # Overridden: added role:admin
-"baremetal:node:list_all": "role:admin or (role:reader and system_scope:all) or (role:service and system_scope:all) or rule:service_role"
+"baremetal:node:list_all": "role:baremetal_node_list_all or (role:reader and system_scope:all) or (role:service and system_scope:all) or rule:service_role"

releasenotes/notes/fix-ironic-horizon-integration-c844d19bd36ed014.yaml

@@ -0,0 +1,11 @@
+---
+upgrade:
+  - |
+    Users with the admin role can can no longer list all baremetal nodes by
+    default. This broke horizon as it tries to collect data for any nodes
+    that it can see. Please add the baremetal_node_list_all role
+    to any users to want this capability; it is not recommened since
+    Horizon will remain broken for them.
+fixes:
+  - |
+    Fixes Horizon Ironic integration which was broken by custom policy.