update valkey to use hostname (agent-substrate#266)

Fixes agent-substrate#225

- [x] Tests pass
- [x] Appropriate changes to documentation are included in the PR

Tested local setup:
```
❯ kubectl exec -n ate-system valkey-cluster-0 -- cat /tmp/valkey.conf | grep cluster-announce
cluster-announce-hostname valkey-cluster-0.valkey-cluster-service.ate-system.svc
cluster-announce-tls-port 6379
cluster-announce-bus-port 16379
```

Separate from this, we should decrease the number of clusters, because
right now all of these get created:
```
❯ kubectl exec -n ate-system valkey-cluster-0 -- valkey-cli --tls --cacert /etc/valkey-ca/ca.crt --cert /run/servicedns.podcert.ate.dev/credential-bundle.pem --key /run/servicedns.podcert.ate.dev/credential-bundle.pem cluster nodes
d6ca3f519ddcf774bc8df68f7b7ab6c82cc35066 10.244.0.25:6379@16379,valkey-cluster-2.valkey-cluster-service.ate-system.svc master - 0 1781721223000 3 connected 10923-16383
6f66ad32594c1a5dc550729434996eb129112a1f 10.244.0.27:6379@16379,valkey-cluster-3.valkey-cluster-service.ate-system.svc slave d6ca3f519ddcf774bc8df68f7b7ab6c82cc35066 0 1781721224614 3 connected
c72d9e9bd165b0f800a135fbda1d8184e8111319 10.244.0.28:6379@16379,valkey-cluster-4.valkey-cluster-service.ate-system.svc slave 1c37cdd7fdcc0a261614a6e3936cc0043fe63d35 0 1781721223594 1 connected
54690be32b6647d43e5e1171e6db92ddf9515ad7 10.244.0.20:6379@16379,valkey-cluster-1.valkey-cluster-service.ate-system.svc master - 0 1781721224614 2 connected 5461-10922
6d862697f8af8750a5280409d1eb2bce9f3f8e0a 10.244.0.26:6379@16379,valkey-cluster-5.valkey-cluster-service.ate-system.svc slave 54690be32b6647d43e5e1171e6db92ddf9515ad7 0 1781721223594 2 connected
1c37cdd7fdcc0a261614a6e3936cc0043fe63d35 10.244.0.22:6379@16379,valkey-cluster-0.valkey-cluster-service.ate-system.svc myself,master - 0 0 1 connected 0-5460
```

agent-substrate#267 is a quick fix to
decrease the pain of setting up the cluster + tearing it down. This
would fix the stale IP issue.

Signed-off-by: npolshakova <nina.polshakova@solo.io>

Author: npolshakova

manifests/ate-install/valkey.yaml

@@ -88,7 +88,20 @@ spec:
       containers:
       - name: valkey
         image: valkey/valkey:8.0
-        command: ["valkey-server", "/etc/valkey/valkey.conf"]
+        command:
+        - /bin/sh
+        - -c
+        - |
+          set -e
+          POD_DNS="${HOSTNAME}.valkey-cluster-service.ate-system.svc"
+          cp /etc/valkey/valkey.conf /tmp/valkey.conf
+          {
+            echo "cluster-announce-hostname ${POD_DNS}"
+            echo "cluster-announce-tls-port 6379"
+            echo "cluster-announce-bus-port 16379"
+            echo "cluster-preferred-endpoint-type hostname"
+          } >> /tmp/valkey.conf
+          exec valkey-server /tmp/valkey.conf
         ports:
         - name: valkey
           containerPort: 6379
@@ -166,11 +179,10 @@ spec:
             done
           done
 
-          echo "All pods resolved. Getting IPs..."
-          POD_IPS=""
+          echo "All pods resolved. Building stable node list..."
+          VALKEY_NODES=""
           for i in 0 1 2 3 4 5; do
-            ip=$(getent hosts valkey-cluster-${i}.valkey-cluster-service.ate-system.svc | awk '{print $1}')
-            POD_IPS="${POD_IPS} ${ip}:6379"
+            VALKEY_NODES="${VALKEY_NODES} valkey-cluster-${i}.valkey-cluster-service.ate-system.svc:6379"
           done
 
           echo "Checking if Valkey cluster is already initialized..."
@@ -187,7 +199,7 @@ spec:
               --cacert /etc/valkey-ca/ca.crt \
               --cert /run/servicedns.podcert.ate.dev/credential-bundle.pem \
               --key /run/servicedns.podcert.ate.dev/credential-bundle.pem \
-              --cluster create ${POD_IPS} \
+              --cluster create ${VALKEY_NODES} \
               --cluster-replicas 1 \
               --cluster-yes
             echo "Cluster initialization complete!"
@@ -210,4 +222,3 @@ spec:
               items:
               - key: ca.crt
                 path: ca.crt
-