### 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/SearchResponse.java
private Status status;
            private Integer totalShards;
            private Integer successfulShards;
            private Integer skippedShards;
            private Integer failedShards;
            private List<ShardSearchFailure> failures;
            private TimeValue took;
            private Boolean timedOut;
            private Cluster original;
            public Builder(Cluster copyFrom) {
                this.original = copyFrom;
            }
            /**
             * @return new Cluster object using the new values passed in via setters
             *         or the values in the "copyFrom" Cluster object set in the
             *         Builder constructor.
             */
            public Cluster build() {
                return new Cluster(
                    original.getClusterAlias(),
                    original.getIndexExpression(),
                    original.isSkipUnavailable(),
                    status != null ? status : original.getStatus(),
                    totalShards != null ? totalShards : original.getTotalShards(),