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/main/java/org/elasticsearch/cluster/coordination/ClusterBootstrapService.java
throw new IllegalArgumentException(
                    "setting [" + INITIAL_MASTER_NODES_SETTING.getKey() + "] contains duplicates: " + initialMasterNodes
                );
            }
            unconfiguredBootstrapTimeout = discoveryIsConfigured(settings) ? null : UNCONFIGURED_BOOTSTRAP_TIMEOUT_SETTING.get(settings);
        }
        this.transportService = transportService;
        this.discoveredNodesSupplier = discoveredNodesSupplier;
        this.isBootstrappedSupplier = isBootstrappedSupplier;
        this.votingConfigurationConsumer = votingConfigurationConsumer;
    }
    public static boolean discoveryIsConfigured(Settings settings) {
        return Stream.of(DISCOVERY_SEED_PROVIDERS_SETTING, DISCOVERY_SEED_HOSTS_SETTING, INITIAL_MASTER_NODES_SETTING)
            .anyMatch(s -> s.exists(settings));
    }
    void logBootstrapState(Metadata metadata) {
        if (metadata.clusterUUIDCommitted()) {
            final var clusterUUID = metadata.clusterUUID();
            if (bootstrapRequirements.isEmpty()) {
                logger.info("this node is locked into cluster UUID [{}] and will not attempt further cluster bootstrapping", clusterUUID);
            } else {
                transportService.getThreadPool()
                    .scheduleWithFixedDelay(() -> logRemovalWarning(clusterUUID), TimeValue.timeValueHours(12), Names.SAME);
                logRemovalWarning(clusterUUID);
            }
        } else {
            logger.info(
                "this node has not joined a bootstrapped cluster yet; [{}] is set to {}",
                INITIAL_MASTER_NODES_SETTING.getKey(),
                bootstrapRequirements