feat: stamp Queue shard status with availability zones

Resolves each shard topic's replica broker IDs (internal/kafka.Admin.
ReplicaBrokerIDs) to the topology.kubernetes.io/zone labels of the nodes
hosting those brokers (ZoneLocator), and writes the result into
ShardStatus.AvailabilityZones each reconcile. Uses mgr.GetAPIReader()
rather than the cached client for the Pod/Node lookups, since the cached
client would otherwise require cluster-wide list/watch RBAC on Pods just
to serve occasional point Gets.

k8s/charts/queue-crd/values.yaml

@@ -8,6 +8,12 @@ image:
 kafkaBrokers: "kmsvc-kafka-bootstrap.sqs.svc.cluster.local:9092"
 redisAddr: "kmsvc-redis-master.sqs.svc.cluster.local:6379"
 
+# Must match kafka-cluster chart's clusterName/derived pool name -- used to
+# resolve "<kafkaClusterName>-<kafkaPoolName>-<brokerID>" broker pod names
+# for AZ-aware Queue status (design.md §2a).
+kafkaClusterName: kmsvc
+kafkaPoolName: kmsvc-pool
+
 resources:
   requests:
     cpu: 100m