The Re-indexing application may be used to index only metadata. You can also exclude the content indexation from the process.
To apply this configuration, set the parameter alfresco.reindex.contentIndexingEnabled to false and change the x.x.x in the .jar file name to the appropriate version number:
java -jar alfresco-elasticsearch-reindexing-x.x.x-app.jar \
--alfresco.reindex.contentIndexingEnabled=false