remove the zone constraint, since the test environment is more limited

Signed-off-by: David Roberts <David.Roberts@orbis.com>

charts/backstage/ci/topologySpreadConstraints-values.yaml

@@ -1,14 +1,5 @@
 backstage:
   topologySpreadConstraints:
-  - maxSkew: 1
-    topologyKey: topology.kubernetes.io/zone
-    whenUnsatisfiable: DoNotSchedule
-    labelSelector:
-      matchLabels:
-        app.kubernetes.io/component: backstage
-    matchLabelKeys:
-      - pod-template-hash
-
   - maxSkew: 1
     topologyKey: kubernetes.io/hostname
     whenUnsatisfiable: DoNotSchedule