### CI Link

https://gradle-enterprise.elastic.co/s/7dleq35dp5stm

### Repro line

./gradlew ':x-pack:plugin:core:test' --tests "org.elasticsearch.xpack.core.ilm.SetSingleNodeAllocateStepTests.testPerformActionAttrsRequestFails" -Dtests.seed=6B438F3C3DADE5D2 -Dtests.locale=nl -Dtests.timezone=Asia/Chongqin

### Does it reproduce?

Yes

### Applicable branches

8.1, 8.0

### Failure history

Seems to fail rarely, but has failed before. Example: https://gradle-enterprise.elastic.co/s/d33b4fzn7yoh6

### Failure excerpt

```
org.elasticsearch.xpack.core.ilm.SetSingleNodeAllocateStepTests > testPerformActionAttrsRequestFails FAILED
    java.lang.AssertionError: Node roles must not be provided as attributes but saw attributes {ml=K}
        at __randomizedtesting.SeedInfo.seed([C679BACC1DA27FA7:CB16887322D9C088]:0)
        at org.elasticsearch.cluster.node.DiscoveryNode.<init>(DiscoveryNode.java:233)
        at org.elasticsearch.cluster.node.DiscoveryNode.<init>(DiscoveryNode.java:175)
```
x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ilm/SetSingleNodeAllocateStepTests.java
.numberOfShards(randomIntBetween(1, 5))
            .numberOfReplicas(randomIntBetween(0, numNodes - 1))
            .build();
        Index index = indexMetadata.getIndex();
        Set<String> validNodeIds = new HashSet<>();
        Settings validNodeSettings = Settings.EMPTY;
        DiscoveryNodes.Builder nodes = DiscoveryNodes.builder();
        for (int i = 0; i < numNodes; i++) {
            String nodeId = "node_id_" + i;
            String nodeName = "node_" + i;
            int nodePort = 9300 + i;
            Map.Entry<String, String> nodeAttr = randomFrom(validAttributes.entrySet());
            Settings nodeSettings = Settings.builder()
                .put(validNodeSettings)
                .put(Node.NODE_NAME_SETTING.getKey(), nodeName)
                .put(Node.NODE_ATTRIBUTES.getKey() + nodeAttr.getKey(), nodeAttr.getValue())
                .build();
            nodes.add(DiscoveryNode.createLocal(nodeSettings, new TransportAddress(TransportAddress.META_ADDRESS, nodePort), nodeId));
            validNodeIds.add(nodeId);
        }
        ImmutableOpenMap.Builder<String, IndexMetadata> indices = ImmutableOpenMap.<String, IndexMetadata>builder()
            .fPut(index.getName(), indexMetadata);
        IndexRoutingTable.Builder indexRoutingTable = IndexRoutingTable.builder(index)
            .addShard(TestShardRouting.newShardRouting(new ShardId(index, 0), "node_id_0", true, ShardRoutingState.STARTED));
        ClusterState clusterState = ClusterState.builder(ClusterState.EMPTY_STATE)
            .metadata(Metadata.builder().indices(indices.build()))
            .nodes(nodes)
            .routingTable(RoutingTable.builder().add(indexRoutingTable).build())
            .build();
        SetSingleNodeAllocateStep step = createRandomInstance();