These tests are ok but could be modernised a bit

- use `safeAwait` instead of awaiting the latch directly
- move assertions into handler, avoiding the need for `responseHolder`
- would it be better to use an `ActionListenerResponseHandler` rather than a raw `TransportResponseHandler`?
server/src/test/java/org/elasticsearch/action/admin/cluster/configuration/TransportClearVotingConfigExclusionsActionTests.java
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.action.admin.cluster.configuration;
import org.apache.lucene.util.SetOnce;
import org.elasticsearch.ElasticsearchTimeoutException;
import org.elasticsearch.action.ActionResponse;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.cluster.ClusterName;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.coordination.CoordinationMetadata;
import org.elasticsearch.cluster.coordination.CoordinationMetadata.VotingConfigExclusion;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.node.DiscoveryNodeUtils;