IOVDbSvc: Fix for extensible folders
For extensible folders, always assign an IOV for the current event/LB even if the current IOV is not open-ended. This covers the use-cases where the IOV may e.g. end at the current run or multi-version folders. See discussion in f7b73216 (comment 3013512)
Relates to ATR-19392
Edited by Frank Winklmeier