Downsampling is broken. Not sure why yet (likely caused by #97557). Invoking the downsample api results into:

```
org.elasticsearch.ElasticsearchSecurityException: no indices permissions found
        at org.elasticsearch.xpack.core.security.support.Exceptions.authorizationError(Exceptions.java:32) ~[?:?]
        at org.elasticsearch.xpack.core.security.authz.accesscontrol.SecurityIndexReaderWrapper.getIndicesAccessControl(SecurityIn
dexReaderWrapper.java:110) ~[?:?]
        at org.elasticsearch.xpack.core.security.authz.accesscontrol.SecurityIndexReaderWrapper.apply(SecurityIndexReaderWrapper.j
ava:76) ~[?:?]
        at org.elasticsearch.xpack.core.security.authz.accesscontrol.SecurityIndexReaderWrapper.apply(SecurityIndexReaderWrapper.j
ava:46) ~[?:?]
        at org.elasticsearch.index.shard.IndexShard.wrapSearcher(IndexShard.java:1590) ~[elasticsearch-8.11.0-SNAPSHOT.jar:?]
        at org.elasticsearch.index.shard.IndexShard.wrapSearcher(IndexShard.java:1561) ~[elasticsearch-8.11.0-SNAPSHOT.jar:?]
        at org.elasticsearch.index.engine.Engine$SearcherSupplier.acquireSearcher(Engine.java:1321) ~[elasticsearch-8.11.0-SNAPSHO
T.jar:?]
        at org.elasticsearch.index.engine.Engine.acquireSearcher(Engine.java:774) ~[elasticsearch-8.11.0-SNAPSHOT.jar:?]
        at org.elasticsearch.index.shard.IndexShard.acquireSearcher(IndexShard.java:1549) ~[elasticsearch-8.11.0-SNAPSHOT.jar:?]
        at org.elasticsearch.xpack.downsample.DownsampleShardIndexer.<init>(DownsampleShardIndexer.java:115) ~[?:?]
        at org.elasticsearch.xpack.downsample.DownsampleShardPersistentTaskExecutor.startDownsampleShardIndexer(DownsampleShardPersistentTaskExecutor.java:111) ~[?:?]
        at org.elasticsearch.xpack.downsample.DownsampleShardPersistentTaskExecutor$1.doRun(DownsampleShardPersistentTaskExecutor.java:87) ~[?:?]
        at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:983) ~[elasticsearch-8.11.0-SNAPSHOT.jar:?]
        at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26) ~[elasticsearch-8.11.0-SNAPSHOT.jar:?]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?]
        at java.lang.Thread.run(Thread.java:1623) ~[?:?]
```
x-pack/plugin/downsample/src/main/java/org/elasticsearch/xpack/downsample/DownsampleShardPersistentTaskExecutor.java
import org.elasticsearch.xpack.core.downsample.DownsampleShardIndexerStatus;
import org.elasticsearch.xpack.core.downsample.DownsampleShardPersistentTaskState;
import org.elasticsearch.xpack.core.downsample.DownsampleShardTask;
import java.util.Arrays;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;
public class DownsampleShardPersistentTaskExecutor extends PersistentTasksExecutor<DownsampleShardTaskParams> {
    private static final Logger logger = LogManager.getLogger(DownsampleShardPersistentTaskExecutor.class);
    private final Client client;
    private final IndicesService indicesService;
    public DownsampleShardPersistentTaskExecutor(
        final Client client,
        final IndicesService indicesService,
        final String taskName,
        final String executorName
    ) {
        super(taskName, executorName);
        this.client = Objects.requireNonNull(client);
        this.indicesService = Objects.requireNonNull(indicesService);
    }
    @Override
    protected void nodeOperation(
        final AllocatedPersistentTask task,
        final DownsampleShardTaskParams params,
        final PersistentTaskState state
    ) {
        
        final SearchRequest searchRequest = new SearchRequest(params.downsampleIndex());
        searchRequest.source().sort(TimeSeriesIdFieldMapper.NAME, SortOrder.DESC).size(1);