### 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/test/java/org/elasticsearch/action/search/SearchResponseTests.java
import org.elasticsearch.search.SearchModule;
import org.elasticsearch.search.aggregations.AggregationsTests;
import org.elasticsearch.search.aggregations.InternalAggregations;
import org.elasticsearch.search.internal.InternalSearchResponse;
import org.elasticsearch.search.profile.SearchProfileResults;
import org.elasticsearch.search.profile.SearchProfileResultsTests;
import org.elasticsearch.search.suggest.Suggest;
import org.elasticsearch.search.suggest.SuggestTests;
import org.elasticsearch.test.ESTestCase;
import org.elasticsearch.test.InternalAggregationTestCase;
import org.elasticsearch.xcontent.NamedXContentRegistry;
import org.elasticsearch.xcontent.ToXContent;
import org.elasticsearch.xcontent.XContentBuilder;
import org.elasticsearch.xcontent.XContentParser;
import org.elasticsearch.xcontent.XContentType;
import org.junit.After;
import org.junit.Before;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;
import static java.util.Collections.emptyList;
import static java.util.Collections.singletonMap;
import static org.elasticsearch.test.XContentTestUtils.insertRandomFields;
import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertToXContentEquivalent;
public class SearchResponseTests extends ESTestCase {