In #86101 we added a warning if bootstrapping was incorrectly configured (and in #92744 we changed it to be emitted every 12h). The logic introduced doesn't take account of `discovery.type: single-node`, so explicitly-single-node clusters will always emit this warning even though they are correctly configured.

Relates https://github.com/elastic/elasticsearch/issues/58393.
server/src/test/java/org/elasticsearch/cluster/coordination/ClusterBootstrapServiceTests.java
import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static java.util.Collections.emptyList;
import static java.util.Collections.emptySet;
import static java.util.Collections.singletonList;
import static org.elasticsearch.cluster.coordination.ClusterBootstrapService.BOOTSTRAP_PLACEHOLDER_PREFIX;
import static org.elasticsearch.cluster.coordination.ClusterBootstrapService.INITIAL_MASTER_NODES_SETTING;
import static org.elasticsearch.cluster.coordination.ClusterBootstrapService.UNCONFIGURED_BOOTSTRAP_TIMEOUT_SETTING;
import static org.elasticsearch.common.settings.Settings.builder;
import static org.elasticsearch.discovery.DiscoveryModule.DISCOVERY_SEED_PROVIDERS_SETTING;
import static org.elasticsearch.discovery.SettingsBasedSeedHostsProvider.DISCOVERY_SEED_HOSTS_SETTING;
import static org.elasticsearch.node.Node.NODE_NAME_SETTING;
import static org.elasticsearch.test.NodeRoles.nonMasterNode;
import static org.hamcrest.Matchers.allOf;
import static org.hamcrest.Matchers.containsInAnyOrder;
import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.greaterThanOrEqualTo;
import static org.hamcrest.Matchers.hasItem;
import static org.hamcrest.Matchers.hasSize;
import static org.hamcrest.Matchers.not;
import static org.hamcrest.Matchers.startsWith;
public class ClusterBootstrapServiceTests extends ESTestCase {