### 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/CCSSingleCoordinatorSearchProgressListener.java
.setTimedOut(false)
                    .build();
                swapped = clusterRef.compareAndSet(curr, updated);
                assert swapped : "compareAndSet in onListShards should never fail due to race condition";
            } while (swapped == false);
        }
    }
    /**
     * Executed when a shard returns a query result.
     *
     * @param shardIndex  The index of the shard in the list provided by {@link SearchProgressListener#onListShards}.
     * @param queryResult QuerySearchResult holding the result for a SearchShardTarget
     */
    @Override
    public void onQueryResult(int shardIndex, QuerySearchResult queryResult) {
        
        
        
        
        if (queryResult.searchTimedOut() && clusters.hasClusterObjects()) {
            SearchShardTarget shardTarget = queryResult.getSearchShardTarget();
            String clusterAlias = shardTarget.getClusterAlias();
            if (clusterAlias == null) {
                clusterAlias = RemoteClusterAware.LOCAL_CLUSTER_GROUP_KEY;
            }
            AtomicReference<SearchResponse.Cluster> clusterRef = clusters.getCluster(clusterAlias);
            boolean swapped;
            do {
                SearchResponse.Cluster curr = clusterRef.get();
                if (curr.isTimedOut()) {