### Description

**Description**

We have been conducting user research on the copy and other aspects of the health API and have a few concrete copy suggestions from the user interviews. 

**StableMasterHealthIndicator**

1. We have user action `UNSTABLE_MASTER_DEPLOYMENT_MANAGEMENT_IMPACT` ([line](https://github.com/elastic/elasticsearch/blob/master/server/src/main/java/org/elasticsearch/cluster/coordination/StableMasterHealthIndicatorService.java#L62). I propose

_Before_: "Scheduled tasks such as Watcher, ILM, and SLM will not work. The _cat APIs will not work." 

_After_:  "Scheduled tasks such as Watcher, Index Lifecycle Management and Snapshot Lifecycle Management will not ...."  instead of using the abbreviations. Some users might not know the terms but at least this gives them more to search on and learn from. 

2. The `UNSTABLE_MASTER_BACKUP_IMPACT` ([line](https://github.com/elastic/elasticsearch/blob/100f5acd345dd13d8c8d17b93392d4b217bc50a2/server/src/main/java/org/elasticsearch/cluster/coordination/StableMasterHealthIndicatorService.java#L64)), I propose making the impact even clearer in laymen terms. 

_Before_: "Snapshot and restore will not work. Searchable snapshots cannot be mounted."
_After_: "Snapshot and restore will not work, your data will not be backed up. Searchable snapshots cannot be mounted, search on backup data will not return results."

I propose we do the same for the messages in the `SlmHealthIndicatorService`, and use the unabbreviated messages where shown to users. 
server/src/main/java/org/elasticsearch/health/node/DiskHealthIndicatorService.java
if (logger.isDebugEnabled()) {
            String nodesMissingHealthInfo = getSortedUniqueValuesString(
                clusterState.getNodes(),
                node -> diskHealthInfoMap.containsKey(node.getId()) == false,
                HealthIndicatorDisplayValues::getNodeName
            );
            if (nodesMissingHealthInfo.isBlank() == false) {
                logger.debug("The following nodes are in the cluster state but not reporting health data: [{}]", nodesMissingHealthInfo);
            }
        }
    }
    /**
     * The disk health analyzer takes into consideration the blocked indices and the health status of the all the nodes and calculates
     * the different aspects of the disk indicator such as the overall status, the symptom, the impacts and the diagnoses.
     */
    static class DiskHealthAnalyzer {
        public static final String INDICES_WITH_READONLY_BLOCK = "indices_with_readonly_block";
        public static final String NODES_WITH_ENOUGH_DISK_SPACE = "nodes_with_enough_disk_space";
        public static final String NODES_OVER_FLOOD_STAGE_WATERMARK = "nodes_over_flood_stage_watermark";
        public static final String NODES_OVER_HIGH_WATERMARK = "nodes_over_high_watermark";
        public static final String NODES_WITH_UNKNOWN_DISK_STATUS = "nodes_with_unknown_disk_status";
        private final ClusterState clusterState;
        private final Set<String> blockedIndices;
        private final List<DiscoveryNode> dataNodes = new ArrayList<>();
        
        private final Map<HealthStatus, List<DiscoveryNode>> masterNodes = new HashMap<>();
        
        private final Map<HealthStatus, List<DiscoveryNode>> otherNodes = new HashMap<>();
        private final Set<DiscoveryNodeRole> affectedRoles = new HashSet<>();
        private final Set<String> indicesAtRisk;