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
bootstrapped.set(false);
        clusterBootstrapService.onFoundPeersUpdated();
        deterministicTaskQueue.runAllTasks();
        assertFalse(bootstrapped.get()); 
    }
    public void testBootstrapsOnDiscoveryOfTwoOfThreeRequiredNodes() {
        final AtomicBoolean bootstrapped = new AtomicBoolean();
        ClusterBootstrapService clusterBootstrapService = new ClusterBootstrapService(
            Settings.builder()
                .putList(INITIAL_MASTER_NODES_SETTING.getKey(), localNode.getName(), otherNode1.getName(), otherNode2.getName())
                .build(),
            transportService,
            () -> singletonList(otherNode1),
            () -> false,
            vc -> {
                assertTrue(bootstrapped.compareAndSet(false, true));
                assertThat(vc.getNodeIds(), hasSize(3));
                assertThat(vc.getNodeIds(), hasItem(localNode.getId()));
                assertThat(vc.getNodeIds(), hasItem(otherNode1.getId()));
                assertThat(vc.getNodeIds(), hasItem(allOf(startsWith(BOOTSTRAP_PLACEHOLDER_PREFIX), containsString(otherNode2.getName()))));
                assertTrue(vc.hasQuorum(Stream.of(localNode, otherNode1).map(DiscoveryNode::getId).toList()));
                assertFalse(vc.hasQuorum(singletonList(localNode.getId())));
                assertFalse(vc.hasQuorum(singletonList(otherNode1.getId())));
            }
        );
        transportService.start();
        clusterBootstrapService.onFoundPeersUpdated();
        deterministicTaskQueue.runAllTasks();
        assertTrue(bootstrapped.get());
        bootstrapped.set(false);