Make TransportAddVotingConfigExclusionsAction retryable (#98568)

The docs for this API say the following:

> If the API fails, you can safely retry it. Only a successful response
> guarantees that the node has been removed from the voting
> configuration and will not be reinstated.

Unfortunately this isn't true today: if the request adds no exclusions
then we do not wait before responding. This commit makes the API wait
until all exclusions are really applied.

Backport of #98386, plus the test changes from #98146 and #98356.

server/src/main/java/org/elasticsearch/action/admin/cluster/configuration/TransportAddVotingConfigExclusionsAction.java

@@ -36,9 +36,9 @@
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
+import java.util.HashSet;
 import java.util.Set;
 import java.util.function.Predicate;
-import java.util.stream.Collectors;
 
 public class TransportAddVotingConfigExclusionsAction extends TransportMasterNodeAction<
     AddVotingConfigExclusionsRequest,
@@ -99,13 +99,14 @@ protected void masterOperation(
 
         clusterService.submitStateUpdateTask("add-voting-config-exclusions", new ClusterStateUpdateTask(Priority.URGENT) {
 
-            private Set<VotingConfigExclusion> resolvedExclusions;
-
             @Override
             public ClusterState execute(ClusterState currentState) {
-                assert resolvedExclusions == null : resolvedExclusions;
                 final int finalMaxVotingConfigExclusions = TransportAddVotingConfigExclusionsAction.this.maxVotingConfigExclusions;
-                resolvedExclusions = resolveVotingConfigExclusionsAndCheckMaximum(request, currentState, finalMaxVotingConfigExclusions);
+                final Set<VotingConfigExclusion> resolvedExclusions = resolveVotingConfigExclusionsAndCheckMaximum(
+                    request,
+                    currentState,
+                    finalMaxVotingConfigExclusions
+                );
 
                 final CoordinationMetadata.Builder builder = CoordinationMetadata.builder(currentState.coordinationMetadata());
                 resolvedExclusions.forEach(builder::addVotingConfigExclusion);
@@ -130,13 +131,13 @@ public void clusterStateProcessed(String source, ClusterState oldState, ClusterS
                     threadPool.getThreadContext()
                 );
 
-                final Set<String> excludedNodeIds = resolvedExclusions.stream()
-                    .map(VotingConfigExclusion::getNodeId)
-                    .collect(Collectors.toSet());
-
                 final Predicate<ClusterState> allNodesRemoved = clusterState -> {
-                    final Set<String> votingConfigNodeIds = clusterState.getLastCommittedConfiguration().getNodeIds();
-                    return excludedNodeIds.stream().noneMatch(votingConfigNodeIds::contains);
+                    final Set<String> votingConfigNodeIds = new HashSet<>();
+                    votingConfigNodeIds.addAll(clusterState.getLastCommittedConfiguration().getNodeIds());
+                    votingConfigNodeIds.addAll(clusterState.getLastAcceptedConfiguration().getNodeIds());
+                    return clusterState.getVotingConfigExclusions()
+                        .stream()
+                        .noneMatch(votingConfigExclusion -> votingConfigNodeIds.contains(votingConfigExclusion.getNodeId()));
                 };
 
                 final Listener clusterStateListener = new Listener() {
@@ -148,20 +149,14 @@ public void onNewClusterState(ClusterState state) {
                     @Override
                     public void onClusterServiceClose() {
                         listener.onFailure(
-                            new ElasticsearchException(
-                                "cluster service closed while waiting for voting config exclusions "
-                                    + resolvedExclusions
-                                    + " to take effect"
-                            )
+                            new ElasticsearchException("cluster service closed while waiting for voting config exclusions to take effect")
                         );
                     }
 
                     @Override
                     public void onTimeout(TimeValue timeout) {
                         listener.onFailure(
-                            new ElasticsearchTimeoutException(
-                                "timed out waiting for voting config exclusions " + resolvedExclusions + " to take effect"
-                            )
+                            new ElasticsearchTimeoutException("timed out waiting for voting config exclusions to take effect")
                         );
                     }
                 };