fix(cli): avoid use of process exit (#9065)
### Description
We've seen segfaults from running `turbo run` on [CI]()
We believe this is due to `process::exit` being called before some
`Drop` implementations have been run. We make sure `Drop`s are run by
returning the exit code instead of exiting.
### Testing Instructions
Run in CI multiple times:
- [Run
1](https://github.com/vercel/turborepo/actions/runs/10562720469/job/29261407172?pr=9065)
- [Run
2](https://github.com/vercel/turborepo/actions/runs/10562720469/job/29262901217?pr=9065)
