Answer
Run ALTER TABLE TRANSACTION_SYS_LOCAL_TAB SHRINK to lower the table's high-water mark and release the freed space back to the tablespace — note this reclaims space within the tablespace but won't shrink the underlying Oracle datafile itself. Separately, make sure the scheduled 'Rebuild Index' job is actually running on a regular basis; indexes aren't automatically kept compact after large volumes of rows are deleted unless that job is scheduled and executing, so a stale index-rebuild schedule can leave both space and performance issues even after the row count itself is brought back under control.