### CI Link

https://gradle-enterprise.elastic.co/s/oyi6h23yl6k3o/tests/:x-pack:qa:full-cluster-restart:v8.11.0%23bwcTest/org.elasticsearch.xpack.restart.CoreFullClusterRestartIT/testClusterState%20%7Bcluster=OLD%7D

### Repro line

./gradlew ':qa:full-cluster-restart:v8.11.0#bwcTest' -Dtests.class="org.elasticsearch.upgrades.FullClusterRestartIT"

### Does it reproduce?

Yes

### Applicable branches

main

### Failure history

_No response_

### Failure excerpt

This test assumes that the index created version in cluster state matches the old node version.

That is no longer true due to the introduction of `IndexVersion`

https://github.com/elastic/elasticsearch/blob/52a6820813577abcb23191d862a01e32e652ed42/qa/full-cluster-restart/src/javaRestTest/java/org/elasticsearch/upgrades/FullClusterRestartIT.java#L435-L440
qa/full-cluster-restart/src/javaRestTest/java/org/elasticsearch/upgrades/FullClusterRestartIT.java
client().performRequest(bulk);
            
            Request reindex = new Request("POST", "/_reindex");
            reindex.setJsonEntity("""
                {
                  "source":{
                    "index":"test_index_old"
                  },
                  "dest":{
                    "index":"test_index_reindex"
                  }
                }""");
            reindex.addParameter("wait_for_completion", "false");
            Map<String, Object> response = entityAsMap(client().performRequest(reindex));
            String taskId = (String) response.get("task");
            
            Request getTask = new Request("GET", "/_tasks/" + taskId);
            getTask.addParameter("wait_for_completion", "true");
            client().performRequest(getTask);
            
            Request getTasksIndex = new Request("GET", "/.tasks");
            getTasksIndex.setOptions(expectVersionSpecificWarnings(v -> {
                v.current(systemIndexWarning);
                v.compatible(systemIndexWarning);
            }));
            getTasksIndex.addParameter("allow_no_indices", "false");
            getTasksIndex.setOptions(expectVersionSpecificWarnings(v -> {
                v.current(systemIndexWarning);
                v.compatible(systemIndexWarning);
            }));