Fix the branches variant for stable branch job

Keeping explicit mention of stable/pike onwards branches with
all current stable + master end up keep updating that in every cycle.
For example stable/rocky is missed for those job.

This commit use explicit exclusion logic for branches so that we do not
need to update that in every cycle.

Change-Id: I8ff9b5f0648d5f4a145e846315807c730bd20f4b
diff --git a/.zuul.yaml b/.zuul.yaml
index b2b59a2..bed19c4 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -77,10 +77,7 @@
     parent: patrole-base
     description: Patrole job for member role.
     # This currently works from stable/pike onward.
-    branches:
-      - master
-      - stable/queens
-      - stable/pike
+    branches: ^(?!stable/ocata).*$
     vars:
       devstack_localrc:
         RBAC_TEST_ROLES: member