### 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
public boolean isMultiField(String field) {
        return mappingLookup().isMultiField(field);
    }
    /**
     * Reload any search analyzers that have reloadable components if resource is {@code null},
     * otherwise only the provided resource is reloaded.
     * @param registry the analysis registry
     * @param resource the name of the reloadable resource or {@code null} if all resources should be reloaded.
     * @param preview {@code false} applies analyzer reloading. {@code true} previews the reloading operation, so analyzers are not reloaded
     *               but the results retrieved. This is useful for understanding analyzers usage in the different indices.
     * @return The names of reloaded resources (or resources that would be reloaded if {@code preview} is true).
     * @throws IOException
     */
    public synchronized List<String> reloadSearchAnalyzers(AnalysisRegistry registry, @Nullable String resource, boolean preview)
        throws IOException {
        logger.info("reloading search analyzers");
        
        return indexAnalyzers.reload(registry, indexSettings, resource, preview);
    }
    /**
     * @return Returns all dynamic templates defined in this mapping.
     */
    public DynamicTemplate[] getAllDynamicTemplates() {
        return documentMapper().mapping().getRoot().dynamicTemplates();
    }
    public MapperRegistry getMapperRegistry() {
        return mapperRegistry;
    }
}