Add index name and uuid in IndexAlreadyExistsException default message

Relates #18274

core/src/main/java/org/elasticsearch/indices/IndexAlreadyExistsException.java

@@ -32,7 +32,7 @@ import java.io.IOException;
 public class IndexAlreadyExistsException extends ElasticsearchException {
 
     public IndexAlreadyExistsException(Index index) {
-        this(index, "already exists");
+        this(index, "index " + index.toString() + " already exists");
     }
 
     public IndexAlreadyExistsException(Index index, String message) {
@@ -48,4 +48,4 @@ public class IndexAlreadyExistsException extends ElasticsearchException {
     public RestStatus status() {
         return RestStatus.BAD_REQUEST;
     }
-}
+}