fix: keep stdin open for persistent tasks (#7196)
### Description
Fixes #7181
Some tools when they are connected to a TTY will take stdin being closed
as a sign that they should shut down. This PR changes our behavior to
keep stdin open for persistent tasks to avoid premature shutdowns.
<img width="649" alt="Screenshot 2024-01-31 at 10 13 00 AM"
src="https://github.com/vercel/turbo/assets/4131117/e7c26b16-2813-428b-9fe3-6eb552d2f102">
### Testing Instructions
Verify that using `vite` no longer immediately exits when invoked using
a pseudoterminal.
<img width="377" alt="Screenshot 2024-01-31 at 10 12 29 AM"
src="https://github.com/vercel/turbo/assets/4131117/8a7f42d3-8a52-489a-9459-b6d711799512">
(`vite` outputs a clear screen sequence resulting in the run prelude
being erased)
Closes TURBO-2208
