### 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
successfulShards != null ? successfulShards : original.getSuccessfulShards(),
                    skippedShards != null ? skippedShards : original.getSkippedShards(),
                    failedShards != null ? failedShards : original.getFailedShards(),
                    failures != null ? failures : original.getFailures(),
                    took != null ? took : original.getTook(),
                    timedOut != null ? timedOut : original.isTimedOut()
                );
            }
            public Builder setStatus(Status status) {
                this.status = status;
                return this;
            }
            public Builder setTotalShards(int totalShards) {
                this.totalShards = totalShards;
                return this;
            }
            public Builder setSuccessfulShards(int successfulShards) {
                this.successfulShards = successfulShards;
                return this;
            }
            public Builder setSkippedShards(int skippedShards) {
                this.skippedShards = skippedShards;
                return this;
            }
            public Builder setFailedShards(int failedShards) {
                this.failedShards = failedShards;
                return this;
            }
            public Builder setFailures(List<ShardSearchFailure> failures) {
                this.failures = failures;