[llvm] Revert "[Lit] Open sub-processes with text=`False`" (PR #196329)

[Benjamin Stott via llvm-commits]

BStott6 wrote:

> LGTM.
> 
> In a case like this I would think it's probably better to fix forward (ideally just let IBM propose a patch), but I guess this is fine too.

Thanks. As it had been 24 hours and I couldn't think of a fix, I thought it better to revert for now and either reland with a fix for z/OS or adapt my design so that these patches are not required - this is possible but will make the IO situation for in-process built-ins more complicated.

https://github.com/llvm/llvm-project/pull/196329