### 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
}
                }
                
                
                return null;
            } else {
                if (key.equals("required")) {
                    
                    
                    
                    if ("_routing".equals(parent) && oldValue != newValue) {
                        throw new MapperParsingException("contradicting `_routing.required` settings");
                    }
                }
                return newValue;
            }
        }
        /**
         * Normally, we don't want to merge raw field mappings, however there are cases where we do, for example - two
         * "object" (or "nested") mappings.
         *
         * @param mappings1 first mapping of a field
         * @param mappings2 second mapping of a field
         * @return {@code true} if the second mapping should be merged into the first mapping
         */
        private boolean shouldMergeFieldMappings(Map<String, Object> mappings1, Map<String, Object> mappings2) {
            String type1 = (String) mappings1.get("type");
            if (type1 == null && mappings1.get("properties") != null) {
                type1 = ObjectMapper.CONTENT_TYPE;
            }