being more selective on the koji tags we trigger on. Fixes T862
    
    Summary: there are now '*-signing-pending' tags in koji which we shouldn't be triggering on. make the logic more picky on what gets through and what doesn't so that we're not triggering on invalid tags. Fixes T862
    
    Differential Revision: https://phab.qadevel.cloud.fedoraproject.org/D1042