In #86101 we added a warning if bootstrapping was incorrectly configured (and in #92744 we changed it to be emitted every 12h). The logic introduced doesn't take account of `discovery.type: single-node`, so explicitly-single-node clusters will always emit this warning even though they are correctly configured.

Relates https://github.com/elastic/elasticsearch/issues/58393.
server/src/test/java/org/elasticsearch/cluster/coordination/ClusterBootstrapServiceTests.java
}
    public void testDoesNotBootstrapIfTwoOfFiveNodesDiscovered() {
        ClusterBootstrapService clusterBootstrapService = new ClusterBootstrapService(
            Settings.builder()
                .putList(
                    INITIAL_MASTER_NODES_SETTING.getKey(),
                    localNode.getName(),
                    otherNode1.getName(),
                    otherNode2.getName(),
                    "not-a-node-1",
                    "not-a-node-2"
                )
                .build(),
            transportService,
            () -> Stream.of(otherNode1).toList(),
            () -> false,
            vc -> {
                throw new AssertionError("should not be called");
            }
        );
        transportService.start();
        clusterBootstrapService.onFoundPeersUpdated();
        deterministicTaskQueue.runAllTasks();
    }
    public void testDoesNotBootstrapIfThreeOfSixNodesDiscovered() {
        ClusterBootstrapService clusterBootstrapService = new ClusterBootstrapService(
            Settings.builder()
                .putList(
                    INITIAL_MASTER_NODES_SETTING.getKey(),
                    localNode.getName(),