### 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
.version(getOldClusterTestVersion())
        .nodes(2)
        .setting("path.repo", () -> repoDirectory.getRoot().getPath())
        .setting("xpack.security.enabled", "false")
        
        .setting("indices.memory.shard_inactive_time", "60m")
        .apply(() -> clusterConfig)
        .feature(FeatureFlag.TIME_SERIES_MODE)
        .build();
    @ClassRule
    public static TestRule ruleChain = RuleChain.outerRule(repoDirectory).around(cluster);
    private String index;
    public FullClusterRestartIT(@Name("cluster") FullClusterRestartUpgradeStatus upgradeStatus) {
        super(upgradeStatus);
    }
    @Override
    protected ElasticsearchCluster getUpgradeCluster() {
        return cluster;
    }
    @Before
    public void setIndex() {
        index = getRootTestName();
    }
    public void testSearch() throws Exception {
        int count;
        if (isRunningAgainstOldCluster()) {
            XContentBuilder mappingsAndSettings = jsonBuilder();
            mappingsAndSettings.startObject();
            {
                mappingsAndSettings.startObject("settings");