Incorrect p-astro, em-bright, and sky map file versions processed by orchestrator

!852 (merged) introduced a bug in earlywarning_preliminary_initial_update_alert in which incorrect versions of p-astro, em-bright, and sky map files are tagged, made public, and added to VOEvents. The versioned filenames as returned by gwcelery.tasks.gracedb.upload need to be processed, not the unqualified filenames, which point to the most recent version.