#98420 verifies that the election scheduler is not running when a cluster is stable, but this assertion does not hold in the `AtomicRegisterCoordinatorTests` suite. This issue tracks the work to investigate and fix up the problem.
server/src/test/java/org/elasticsearch/cluster/coordination/AtomicRegisterCoordinatorTests.java
import org.elasticsearch.cluster.coordination.stateless.DisruptibleHeartbeatStore;
import org.elasticsearch.cluster.coordination.stateless.Heartbeat;
import org.elasticsearch.cluster.coordination.stateless.HeartbeatStore;
import org.elasticsearch.cluster.coordination.stateless.SingleNodeReconfigurator;
import org.elasticsearch.cluster.coordination.stateless.StoreHeartbeatService;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
import org.elasticsearch.common.settings.ClusterSettings;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.gateway.ClusterStateUpdaters;
import org.elasticsearch.test.MockLogAppender;
import org.elasticsearch.test.junit.annotations.TestLogging;
import org.elasticsearch.threadpool.ThreadPool;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.OptionalLong;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.BooleanSupplier;
import java.util.function.Function;
import java.util.function.LongSupplier;
import static org.elasticsearch.cluster.coordination.CoordinationStateTests.clusterState;
import static org.elasticsearch.cluster.coordination.stateless.StoreHeartbeatService.HEARTBEAT_FREQUENCY;
import static org.elasticsearch.cluster.coordination.stateless.StoreHeartbeatService.MAX_MISSED_HEARTBEATS;
@TestLogging(reason = "these tests do a lot of log-worthy things but we usually don't care", value = "org.elasticsearch:FATAL")