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
final DownsampleShardPersistentTaskState initialState = lastDownsampleTsidHits.length == 0
            ? new DownsampleShardPersistentTaskState(DownsampleShardIndexerStatus.INITIALIZED, null)
            : new DownsampleShardPersistentTaskState(
                DownsampleShardIndexerStatus.STARTED,
                Arrays.stream(lastDownsampleTsidHits).findFirst().get().field("_tsid").getValue()
            );
        final DownsampleShardIndexer downsampleShardIndexer = new DownsampleShardIndexer(
            (DownsampleShardTask) task,
            client,
            getIndexService(indicesService, params),
            params.shardId(),
            params.downsampleIndex(),
            params.downsampleConfig(),
            params.metrics(),
            params.labels(),
            initialState
        );
        try {
            downsampleShardIndexer.execute();
            task.markAsCompleted();
        } catch (final DownsampleShardIndexerException e) {
            if (e.isRetriable()) {
                logger.error("Downsampling task [" + task.getPersistentTaskId() + " retriable failure [" + e.getMessage() + "]");
                task.markAsLocallyAborted(e.getMessage());
            } else {
                logger.error("Downsampling task [" + task.getPersistentTaskId() + " non retriable failure [" + e.getMessage() + "]");
                task.markAsFailed(e);
            }
        } catch (final Exception e) {
            logger.error("Downsampling task [" + task.getPersistentTaskId() + " non-retriable failure [" + e.getMessage() + "]");