Update ResulsDB directive to work with API v2.0
    
    Once we deploy new ExecDB, I'd like to move the "create_resultsdb_group" to
    ExecDB, which would actually create the group, with a meaningfull description,
    and resultsdb directive would then only use the `uuid` to reference it.
    
    Differential Revision: https://phab.qadevel.cloud.fedoraproject.org/D1019