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
final Settings.Builder settings = Settings.builder()
            .put(DiscoveryModule.DISCOVERY_TYPE_SETTING.getKey(), DiscoveryModule.SINGLE_NODE_DISCOVERY_TYPE)
            .put(NODE_NAME_SETTING.getKey(), localNode.getName())
            .put(nonMasterNode());
        assertThat(
            expectThrows(
                IllegalArgumentException.class,
                () -> new ClusterBootstrapService(settings.build(), transportService, Collections::emptyList, () -> false, vc -> fail())
            ).getMessage(),
            containsString("node with [discovery.type] set to [single-node] must be master-eligible")
        );
    }
    public void testBootstrapStateLogging() {
        final var mockAppender = new MockLogAppender();
        try (var ignored = mockAppender.capturing(ClusterBootstrapService.class)) {
            mockAppender.addExpectation(
                new MockLogAppender.SeenEventExpectation(
                    "fresh node message",
                    ClusterBootstrapService.class.getCanonicalName(),
                    Level.INFO,
                    "this node has not joined a bootstrapped cluster yet; [cluster.initial_master_nodes] is set to [node1, node2]"
                )
            );
            final var metadataBuilder = Metadata.builder().clusterUUIDCommitted(false);
            if (randomBoolean()) {
                metadataBuilder.clusterUUID(UUIDs.randomBase64UUID(random()));
            }
            new ClusterBootstrapService(
                Settings.builder().putList(INITIAL_MASTER_NODES_SETTING.getKey(), "node1", "node2").build(),
                transportService,