Adjust German Translation of EU Certificate (#3520)

Part 3/3 - Old German translation of certificate "EU Digitales COVID-Zertifikat“ is replaced by new official name „Digitales COVID-Zertifikat der EU“. Attention: This is only valid for the German translation. Related Jira issue: https://jira-ibs.wbs.net.sap/browse/EXPOSUREAPP-8014