### 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
if (metadataFieldMapper != null) {
                    metadataMappers.put(metadataFieldMapper.getClass(), metadataFieldMapper);
                }
            }
        } else {
            metadataMappers.putAll(existingMapper.mapping().getMetadataMappersMap());
        }
        return metadataMappers;
    }
    /**
     * Parses the mappings (formatted as JSON) into a map
     */
    public static Map<String, Object> parseMapping(NamedXContentRegistry xContentRegistry, String mappingSource) throws IOException {
        if ("{}".equals(mappingSource)) {
            
            return Map.of();
        }
        try (XContentParser parser = XContentType.JSON.xContent().createParser(parserConfig(xContentRegistry), mappingSource)) {
            return parser.map();
        }
    }
    /**
     * Parses the mappings (formatted as JSON) into a map
     */
    public static Map<String, Object> parseMapping(NamedXContentRegistry xContentRegistry, CompressedXContent mappingSource)
        throws IOException {
        try (
            InputStream in = CompressorFactory.COMPRESSOR.threadLocalInputStream(mappingSource.compressedReference().streamInput());
            XContentParser parser = XContentType.JSON.xContent().createParser(parserConfig(xContentRegistry), in)