Leave the underlying --launcher-opts in place.

Looks a bit busier, but this is just due to moving code in a tabstop.

This removes the -B option to slurmctld as well, update
the man page as appropriate.

This was developed after the commit that follows, but the order was
switched around to make sure both commits compile cleanly.

All of these select_g_select_jobinfo_get/set() calls are no-ops.

Also remove a call to SELECT_JOBDATA_IONODES which is a no op.

With BG removed, this exposes that this function call had been reused
for select/alps for a different purpose. Rename the function to make
this clear, and strip out some unnecessary handling in other_select()
since this is a no op everywhere else.