htcondor: adapt snakemake cmd
htcondor: adapt snakemake cmd

Remove workflow workspace prefix from `touch` commands.

closes reanahub/reana-workflow-engine-snakemake#27

reanahub/reana-job-controller,tiborsimko/reana-job-controller,reanahub/reana-job-controller,tiborsimko/reana-job-controller