arrproxy: v0.6.0 self-migrating, drop external migrate Job

Bump arrproxy-api and arrproxy-ui to v0.6.0 and remove the psql migrate Job
plus its migrations ConfigMap. v0.6.0 applies its own schema at startup under
a Postgres advisory lock and holds /readyz until it is current, so the
external hook is dead weight and a drift trap.

apps/base/arrstack/arrproxy/ui-deployment.yaml

@@ -31,7 +31,7 @@ spec:
           type: RuntimeDefault
       containers:
         - name: ui
-          image: artifactapi.k8s.syd1.au.unkin.net/docker-internal/arrproxy-ui:v0.5.0
+          image: artifactapi.k8s.syd1.au.unkin.net/docker-internal/arrproxy-ui:v0.6.0
           imagePullPolicy: IfNotPresent
           ports:
             - containerPort: 8080