### Description

I was just looking at some Elasticsearch that had lots of "Improve "reloading search analyzers" logs coming from `MapperService` at the INFO level. In my particular case, it was being emitted because analyzers are reloaded as part of doing a recovery. This log is not really helpful as-is, I think we need to do the following:
 - Switch the level to DEBUG, it's not important enough to warrant an INFO log.
 - Add which index reloaded its search analyzers to the log.

What do you think?
server/src/main/java/org/elasticsearch/index/mapper/MapperService.java
private static final XContentHelper.CustomMerge INSTANCE = new RawFieldMappingMerge();
        private static final Set<String> MERGEABLE_OBJECT_TYPES = Set.of(ObjectMapper.CONTENT_TYPE, NestedObjectMapper.CONTENT_TYPE);
        private RawFieldMappingMerge() {}
        @SuppressWarnings("unchecked")
        @Override
        public Object merge(String parent, String key, Object oldValue, Object newValue) {
            if (oldValue instanceof Map && newValue instanceof Map) {
                if ("properties".equals(parent)) {
                    
                    Map<String, Object> baseMap = (Map<String, Object>) oldValue;
                    Map<String, Object> mapToMerge = (Map<String, Object>) newValue;
                    if (shouldMergeFieldMappings(baseMap, mapToMerge)) {
                        
                        
                        Map<String, Object> mergedMappings = new HashMap<>();
                        
                        if (baseMap.containsKey("properties")) {
                            mergedMappings.put("properties", new HashMap<>((Map<String, Object>) baseMap.get("properties")));
                        }
                        
                        if (baseMap.containsKey("subobjects")) {
                            mergedMappings.put("subobjects", baseMap.get("subobjects"));
                        }
                        
                        XContentHelper.merge(key, mergedMappings, mapToMerge, INSTANCE);
                        return mergedMappings;
                    } else {
                        
                        return mapToMerge;