### 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
merge(mappingMetadata.type(), mappingMetadata.source(), reason);
        }
    }
    /**
     * Merging the provided mappings. Actual merging is done in the raw, non-parsed, form of the mappings. This allows to do a proper bulk
     * merge, where parsing is done only when all raw mapping settings are already merged.
     */
    public DocumentMapper merge(String type, List<CompressedXContent> mappingSources, MergeReason reason) {
        final DocumentMapper currentMapper = this.mapper;
        if (currentMapper != null && mappingSources.size() == 1 && currentMapper.mappingSource().equals(mappingSources.get(0))) {
            return currentMapper;
        }
        Map<String, Object> mergedRawMapping = null;
        for (CompressedXContent mappingSource : mappingSources) {
            Map<String, Object> rawMapping = MappingParser.convertToMap(mappingSource);
            
            if (rawMapping.containsKey(type)) {
                if (rawMapping.size() > 1) {
                    throw new MapperParsingException("cannot merge a map with multiple roots, one of which is [" + type + "]");
                }
            } else {
                rawMapping = Map.of(type, rawMapping);
            }
            if (mergedRawMapping == null) {
                mergedRawMapping = rawMapping;
            } else {
                XContentHelper.merge(type, mergedRawMapping, rawMapping, RawFieldMappingMerge.INSTANCE);
            }
        }
        if (mergedRawMapping != null && mergedRawMapping.size() > 1) {