test: Only test against latest ZooKeeper (#998)

NiFi encourages using Kubernetes leases instead of ZooKeeper in Kubernetes clusters. We should then only test against the latest.

This came up in this [slack thread](https://stackable-workspace.slack.com/archives/C031NP72H7T/p1790080843987429)

Author: NickLarsenNZ

tests/templates/kuttl/smoke/20-install-zookeeper.yaml.j2

@@ -6,7 +6,7 @@ metadata:
   name: zookeeper
 spec:
   image:
-    productVersion: "{{ test_scenario['values']['zookeeper'] }}"
+    productVersion: "{{ test_scenario['values']['zookeeper-latest'] }}"
     pullPolicy: IfNotPresent
   clusterConfig:
 {% if lookup('env', 'VECTOR_AGGREGATOR') %}

tests/test-definition.yaml

@@ -33,10 +33,6 @@ dimensions:
     values:
       - "false"
       - "true"
-  - name: zookeeper
-    values:
-      - 3.9.5
-      - 3.9.6
   - name: zookeeper-latest
     values:
       - 3.9.6
@@ -93,7 +89,7 @@ tests:
   - name: smoke
     dimensions:
       - nifi
-      - zookeeper
+      - zookeeper-latest
       - use-zookeeper-manager
       - listener-class
       - openshift