This acts as a revert of b83747a8a6 and 9886744a36. As pointed out
by Noah, HEAD and REL_17_STABLE are in a weird state where the code
paths adding /D would limit the spawn of child processes, but we still
have code paths where the spawn of more than one child process would be
possible.
Let's remove these /D switches for now, to bring back the code into a
state consistent with how autorun is configured on a Windows host.
Reported-by: Noah Misch
Discussion: https://postgr.es/m/20240630021211.f3.nmisch@google.com
Backpatch-through: 17
fa1a63dffc