### 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
countRequest.addParameter("size", "0");
        Map<String, Object> countResponse = entityAsMap(client().performRequest(countRequest));
        assertTotalHits(count, countResponse);
        
        Request addRoutingSettings = new Request("PUT", "/_cluster/settings");
        addRoutingSettings.setJsonEntity(Strings.format("""
            {"persistent": {"cluster.routing.allocation.exclude.test_attr": "%s"}}
            """, getOldClusterVersion()));
        client().performRequest(addRoutingSettings);
        
        XContentBuilder templateBuilder = JsonXContent.contentBuilder().startObject();
        templateBuilder.field("index_patterns", "evil_*"); 
        templateBuilder.startObject("settings");
        {
            templateBuilder.field("number_of_shards", 1);
        }
        templateBuilder.endObject();
        templateBuilder.startObject("mappings");
        {
            {
                templateBuilder.startObject("_source");
                {
                    templateBuilder.field("enabled", true);
                }
                templateBuilder.endObject();
            }
        }
        templateBuilder.endObject();
        templateBuilder.startObject("aliases");
        {