In https://github.com/elastic/elasticsearch/pull/78547 we introduced batching for the ILM master tasks that occur on the happy path. However if a high-shard-count cluster encounters problems while doing ILM-related things—perhaps some nodes are temporarily unavailable for taking a snapshot—then we process the resulting `ilm-retry-failed-step` and `ilm-move-to-error-step` tasks one-by-one which can significantly delay the cluster's recovery from its problems.

We should batch these things together too.

It looks like we also enqueue duplicate `ilm-retry-failed-step` on each poll interval too, although we do appear to treat the duplicates as no-ops at execution time.

Relates https://github.com/elastic/elasticsearch/issues/77466
x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/IndexLifecycleRunner.java
registerSuccessfulOperation(indexMetadata);
                if (newStepKey != null && newStepKey != TerminalPolicyStep.KEY && indexMetadata != null) {
                    maybeRunAsyncAction(clusterState, indexMetadata, policy, newStepKey);
                }
            })
        );
    }
    /**
     * Move the index to the ERROR step.
     */
    private void moveToErrorStep(Index index, String policy, Step.StepKey currentStepKey, Exception e) {
        logger.error(
            new ParameterizedMessage(
                "policy [{}] for index [{}] failed on step [{}]. Moving to ERROR step",
                policy,
                index.getName(),
                currentStepKey
            ),
            e
        );
        clusterService.submitStateUpdateTask(
            String.format(
                Locale.ROOT,
                "ilm-move-to-error-step {policy [%s], index [%s], currentStep [%s]}",
                policy,
                index.getName(),
                currentStepKey
            ),
            new MoveToErrorStepUpdateTask(index, policy, currentStepKey, e, nowSupplier, stepRegistry::getStep, clusterState -> {
                IndexMetadata indexMetadata = clusterState.metadata().index(index);