Implement static ElasticSearch Client for TG-publish
See /kolibri-tgpublish-service/src/main/java/de/langzeitarchivierung/kolibri/actionmodule/textgrid/publish/CopyElasticSearchIndex.java and /kolibri-tgpublish-service/src/main/java/de/langzeitarchivierung/kolibri/actionmodule/textgrid/publish/ReleaseNearlyPublishedRelation.java