If no ckpt server used, don't try to remove remote ckpt on exit.  #3919
If no ckpt server used, don't try to remove remote ckpt on exit.  #3919

This results in the sched logs filling up with spurious, confusing
error messages.

zhangzhehust/htcondor,djw8605/htcondor,htcondor/htcondor,djw8605/htcondor,zhangzhehust/htcondor,neurodebian/htcondor,zhangzhehust/htcondor,htcondor/htcondor,djw8605/htcondor,neurodebian/htcondor,neurodebian/htcondor,djw8605/htcondor,neurodebian/htcondor,djw8605/htcondor,htcondor/htcondor,djw8605/htcondor,zhangzhehust/htcondor,neurodebian/htcondor,djw8605/htcondor,htcondor/htcondor,djw8605/htcondor,zhangzhehust/htcondor,zhangzhehust/htcondor,zhangzhehust/htcondor,htcondor/htcondor,zhangzhehust/htcondor,neurodebian/htcondor,zhangzhehust/htcondor,htcondor/htcondor,neurodebian/htcondor,neurodebian/htcondor,djw8605/htcondor,htcondor/htcondor,htcondor/htcondor,neurodebian/htcondor