### 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
int nodePort = 9300 + i;
            Settings nodeSettings = Settings.builder()
                .put(Node.NODE_NAME_SETTING.getKey(), nodeName)
                .put(Node.NODE_ATTRIBUTES.getKey() + attribute, invalidAttr)
                .build();
            newNodeIds.add(nodeId);
            nodes.add(
                new DiscoveryNode(
                    Node.NODE_NAME_SETTING.get(nodeSettings),
                    nodeId,
                    new TransportAddress(TransportAddress.META_ADDRESS, nodePort),
                    Node.NODE_ATTRIBUTES.getAsMap(nodeSettings),
                    DiscoveryNode.getRolesFromSettings(nodeSettings),
                    Version.CURRENT
                )
            );
        }
        Set<String> oldNodeIds = new HashSet<>();
        for (int i = 0; i < numOldNodes; i++) {
            String nodeId = "old_node_id_" + i;
            String nodeName = "old_node_" + i;
            int nodePort = 9300 + numNewNodes + i;
            Settings nodeSettings = Settings.builder()
                .put(Node.NODE_NAME_SETTING.getKey(), nodeName)
                .put(Node.NODE_ATTRIBUTES.getKey() + attribute, validAttr)
                .build();
            oldNodeIds.add(nodeId);
            nodes.add(
                new DiscoveryNode(
                    Node.NODE_NAME_SETTING.get(nodeSettings),