When executed with force_parallel_mode=regress, the function was exiting
too early and thus failed to print the worker stats. Fixed by making it
more like show_sort_info.

Discussion: https://postgr.es/m/CAPpHfds1waRZ=NOmueYq0sx1ZSCnt+5QJvizT8ndT2=etZEeAQ@mail.gmail.com