fix: admin and member gates are broken

The patrole-admin and patrole-member gates are broken because they
are trying to test a policy action ('os_compute_api:os-services') that
was changed in the Ussuri release. This commit adds a new policy feature
flag so that this policy test is backwards compatible.

Change-Id: Ia80279ae8ffcc17f10bed05338c41d0c23eea063
diff --git a/releasenotes/notes/changed_nova_policies_ussuri-177582b3ded63411.yaml b/releasenotes/notes/changed_nova_policies_ussuri-177582b3ded63411.yaml
new file mode 100644
index 0000000..5362f04
--- /dev/null
+++ b/releasenotes/notes/changed_nova_policies_ussuri-177582b3ded63411.yaml
@@ -0,0 +1,13 @@
+---
+features:
+  - |
+    A new policy feature flag called
+    ``[policy_feature_flag].changed_nova_policies_ussuri`` has been added to
+    Patrole's config to handle Nova policies changed in Ussuri. The policy
+    feature flag is applied to tests that use policies changed in Ussuri,
+    including the following:
+
+      - os_compute_api:os-services
+
+    Note that not all changed policies are included above because test coverage
+    is missing for them.