This will test that the force option works when there is an active backend
connected to the database being dropped.

Author: Pavel Stehule and Vignesh C
Reviewed-by: Amit Kapila and Vignesh C
Discussion: https://postgr.es/m/CAP_rwwmLJJbn70vLOZFpxGw3XD7nLB_7+NKz46H5EOO2k5H7OQ@mail.gmail.com