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 long timeout;
        if (randomBoolean()) {
            timeout = UNCONFIGURED_BOOTSTRAP_TIMEOUT_SETTING.get(Settings.EMPTY).millis();
        } else {
            timeout = randomLongBetween(1, 10000);
            settings.put(UNCONFIGURED_BOOTSTRAP_TIMEOUT_SETTING.getKey(), timeout + "ms");
        }
        final AtomicReference<Supplier<Iterable<DiscoveryNode>>> discoveredNodesSupplier = new AtomicReference<>(() -> {
            throw new AssertionError("should not be called yet");
        });
        final AtomicBoolean bootstrapped = new AtomicBoolean();
        ClusterBootstrapService clusterBootstrapService = new ClusterBootstrapService(
            settings.build(),
            transportService,
            () -> discoveredNodesSupplier.get().get(),
            () -> false,
            vc -> {
                assertTrue(bootstrapped.compareAndSet(false, true));
                assertThat(
                    vc.getNodeIds(),
                    equalTo(Stream.of(localNode, otherNode1, otherNode2).map(DiscoveryNode::getId).collect(Collectors.toSet()))
                );
                assertThat(deterministicTaskQueue.getCurrentTimeMillis(), greaterThanOrEqualTo(timeout));
            }
        );
        deterministicTaskQueue.scheduleAt(
            timeout - 1,
            () -> discoveredNodesSupplier.set(() -> Stream.of(localNode, otherNode1, otherNode2).collect(Collectors.toSet()))
        );
        transportService.start();