feat(postgres): Avoid a postgres cluster on a single node

This patch makes sure that a PostgreSQL cluster doesn't end up on a single
node. This is done by defaulting to a pod anti-affinity based on the
kubernetes hostname label, that should make sure, that all stateful sets
are distributed properly.

infrastructure/postgres/release.yaml

@@ -24,3 +24,5 @@ spec:
       runAsUser: null
       readOnlyRootFilesystem: true
       allowPrivilegeEscalation: false
+    configKubernetes:
+      enable_pod_antiaffinity: true