fix: remove downsample_indexer

Author: salvatore-campagna

x-pack/plugin/downsample/src/main/java/org/elasticsearch/xpack/downsample/TransportDownsampleAction.java

@@ -103,7 +103,7 @@
 /**
  * The master downsample action that coordinates
  *  -  creating the downsample index
- *  -  instantiating {@link DownsampleShardIndexer}s to index downsample documents
+ *  -  instantiating {@link org.elasticsearch.persistent.PersistentTasksExecutor} to start a persistent downsample task
  *  -  cleaning up state
  */
 public class TransportDownsampleAction extends AcknowledgedTransportMasterNodeAction<DownsampleAction.Request> {

x-pack/plugin/security/qa/operator-privileges-tests/src/javaRestTest/java/org/elasticsearch/xpack/security/operator/Constants.java

@@ -556,7 +556,6 @@ public class Constants {
         "indices:admin/xpack/ccr/put_follow",
         "indices:admin/xpack/ccr/unfollow",
         "indices:admin/xpack/downsample",
-        "indices:admin/xpack/downsample_indexer",
         "indices:data/read/downsample_delegate",
         "indices:data/read/async_search/delete",
         "indices:data/read/async_search/get",