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
);
                    }
                    /*
                     * Sanity checks to ensure that we receive documents in the correct order
                     * - _tsid must be sorted in ascending order
                     * - @timestamp must be sorted in descending order within the same _tsid
                     */
                    BytesRef lastTsid = downsampleBucketBuilder.tsid();
                    assert lastTsid == null || lastTsid.compareTo(tsid) <= 0
                        : "_tsid is not sorted in ascending order: ["
                            + DocValueFormat.TIME_SERIES_ID.format(lastTsid)
                            + "] -> ["
                            + DocValueFormat.TIME_SERIES_ID.format(tsid)
                            + "]";
                    assert tsid.equals(lastTsid) == false || lastTimestamp >= timestamp
                        : "@timestamp is not sorted in descending order: ["
                            + timestampFormat.format(lastTimestamp)
                            + "] -> ["
                            + timestampFormat.format(timestamp)
                            + "]";
                    lastTimestamp = timestamp;
                    if (tsidChanged || downsampleBucketBuilder.timestamp() != lastHistoTimestamp) {
                        
                        if (downsampleBucketBuilder.isEmpty() == false) {
                            XContentBuilder doc = downsampleBucketBuilder.buildDownsampleDocument();
                            indexBucket(doc);
                        }
                        
                        if (tsidChanged) {
                            downsampleBucketBuilder.resetTsid(tsid, tsidOrd, lastHistoTimestamp);