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/DownsampleShardIndexer.java
public void beforeBulk(long executionId, BulkRequest request) {
                task.addNumSent(request.numberOfActions());
                task.setBeforeBulkInfo(
                    new DownsampleBeforeBulkInfo(
                        client.threadPool().absoluteTimeInMillis(),
                        executionId,
                        request.estimatedSizeInBytes(),
                        request.numberOfActions()
                    )
                );
            }
            @Override
            public void afterBulk(long executionId, BulkRequest request, BulkResponse response) {
                long bulkIngestTookMillis = response.getIngestTookInMillis() >= 0 ? response.getIngestTookInMillis() : 0;
                long bulkTookMillis = response.getTook().getMillis();
                task.addNumIndexed(request.numberOfActions());
                task.setAfterBulkInfo(
                    new DownsampleAfterBulkInfo(
                        client.threadPool().absoluteTimeInMillis(),
                        executionId,
                        bulkIngestTookMillis,
                        bulkTookMillis,
                        response.hasFailures(),
                        response.status().getStatus()
                    )
                );
                task.updateBulkInfo(bulkIngestTookMillis, bulkTookMillis);
                if (response.hasFailures()) {
                    List<BulkItemResponse> failedItems = Arrays.stream(response.getItems()).filter(BulkItemResponse::isFailed).toList();
                    task.addNumFailed(failedItems.size());