### 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
static int extractTotalHits(Map<?, ?> response) {
        return (Integer) XContentMapValues.extractValue("hits.total.value", response);
    }
    /**
     * Tests that a single document survives. Super basic smoke test.
     */
    public void testSingleDoc() throws IOException {
        String docLocation = "/" + index + "/_doc/1";
        String doc = "{\"test\": \"test\"}";
        if (isRunningAgainstOldCluster()) {
            Request createDoc = new Request("PUT", docLocation);
            createDoc.setJsonEntity(doc);
            client().performRequest(createDoc);
        }
        Request request = new Request("GET", docLocation);
        assertThat(toStr(client().performRequest(request)), containsString(doc));
    }
    /**
     * Tests that a single empty shard index is correctly recovered. Empty shards are often an edge case.
     */
    public void testEmptyShard() throws IOException {
        final String indexName = "test_empty_shard";
        if (isRunningAgainstOldCluster()) {
            Settings.Builder settings = Settings.builder()
                .put(IndexMetadata.INDEX_NUMBER_OF_SHARDS_SETTING.getKey(), 1)
                .put(IndexMetadata.INDEX_NUMBER_OF_REPLICAS_SETTING.getKey(), 1)