### Description

`SearchResponse.Clusters` currently uses a `HashMap<String, AtomicReference>` for storing Cluster objects. The AtomicReference CAS swaps are done in a do/while loop in most cases (e.g., in `CCSSingleCoordinatorSearchProgressListener`).

This can be replaced with a `ConcurrentHashMap` in conjunction with either `compute()` method or the `replace(key, assumed_previous_value, value)` method for atomically swapping in a new Cluster object with a CAS operation, assuring that the updates don't lose data from competing threads doing separate Cluster object updates.

See: https://github.com/elastic/elasticsearch/pull/98457/files#r1310467586 
server/src/main/java/org/elasticsearch/action/search/TransportSearchAction.java
clusterRef.updateAndGet(
                orig -> new SearchResponse.Cluster.Builder(orig).setStatus(SearchResponse.Cluster.Status.SUCCESSFUL)
                    .setTotalShards(0)
                    .setSuccessfulShards(0)
                    .setSkippedShards(0)
                    .setFailedShards(0)
                    .setFailures(Collections.emptyList())
                    .setTook(new TimeValue(timeProvider.buildTookInMillis()))
                    .setTimedOut(false)
                    .build()
            );
        }
    }
    void executeLocalSearch(
        Task task,
        SearchTimeProvider timeProvider,
        SearchRequest searchRequest,
        OriginalIndices localIndices,
        ClusterState clusterState,
        SearchResponse.Clusters clusterInfo,
        SearchContextId searchContext,
        SearchPhaseProvider searchPhaseProvider
    ) {
        executeSearch(
            (SearchTask) task,
            timeProvider,
            searchRequest,
            localIndices,
            Collections.emptyList(),
            (clusterName, nodeId) -> null,