[Pending Cluster Tasks][ILM] Add Index Name

[stefnestor]

Description

👋🏼 howdy, team!

Would you kindly consider adding in the index name to Cluster Pending Tasks for ilm-execute-cluster-state-steps (related code) similar as is done for ilm-set-step-info higher in file

else if (currentStep instanceof ClusterStateActionStep || currentStep instanceof ClusterStateWaitStep) {
    logger.debug("[{}] running policy with current-step [{}]", indexMetadata.getIndex().getName(), currentStep.getKey());
    submitUnlessAlreadyQueued(
-        String.format(Locale.ROOT, "ilm-execute-cluster-state-steps [%s]", currentStep),
+        String.format(Locale.ROOT, "ilm-execute-cluster-state-steps {policy [%s], index [%s] currentStep [%s]}", 
+            policy, 
+            indexMetadata.getIndex().getName(), 
+            currentStep
+        ),
        new ExecuteStepsUpdateTask(policy, indexMetadata.getIndex(), currentStep, stepRegistry, this, nowSupplier)
    );

Current code's emitted example is non-informative if tasks are blocked/queued(; example is just example, arguably not itself blocked):

{
  "insert_order": 9659,
  "priority": "NORMAL",
-  "source": "ilm-execute-cluster-state-steps [{\"phase\":\"delete\",\"action\":\"wait_for_snapshot\",\"name\":\"wait-for-snapshot\"} => {\"phase\":\"delete\",\"action\":\"delete\",\"name\":\"wait-for-shard-history-leases\"}]",
  "executing": false,
  "time_in_queue_millis": 302298,
  "time_in_queue": "5m"
}

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[DaveCTurner]

This highlights a general problem with the descriptions for cluster tasks being a bit of a mess. Originally source was intended as a key for grouping similar tasks together (e.g. shard-failed) but many implementations put too much detail there for grouping to be meaningful. But then again that detail is useful and today there's nowhere else to put it. I sketched out an improvement that adds a better separation between source and detail at #102613 which would help with this kind of thing.