Remove shadow forking for proxy-related tasks. HTCONDOR-519
Remove shadow forking for proxy-related tasks. HTCONDOR-519

Now that we don't use GSI for proxy tasks, doing them in the main shadow
process has only a minimal memory hit.

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor