Fix SIGTTIN handling (#9681)

# Description
Due to a typo? in the
[reference](https://www.gnu.org/software/libc/manual/html_node/Initializing-the-Shell.html)
used to implement SIGTTIN handling, nushell will crash when being sent
to the background from within another shell.

For example, currently in bash:
```bash
$ nu -n &
[1] 176058
$ ERROR: failed to SIGTTIN ourselves

[1]+  Exit 1                  nu -n
$
```

Now fixed:
```bash
$ nu -n &
[1] 178788
$ jobs
[1]+  Stopped                 nu -n
$
```

For further reference, this is how
[fish](493cbeb84c/src/reader.cpp (L2571))
does it.

# User-Facing Changes
Bug fix only -- users should now be able to send nushell to the
background.

src/terminal.rs

@@ -59,12 +59,11 @@ fn take_control(interactive: bool) {
         }
     }
 
-    let mut success = false;
     for _ in 0..4096 {
         match unistd::tcgetpgrp(nix::libc::STDIN_FILENO) {
             Ok(owner_pgid) if owner_pgid == shell_pgid => {
-                success = true;
-                break;
+                // success
+                return;
             }
             Ok(owner_pgid) if owner_pgid == Pid::from_raw(0) => {
                 // Zero basically means something like "not owned" and we can just take it
@@ -80,7 +79,7 @@ fn take_control(interactive: bool) {
             }
             _ => {
                 // fish also has other heuristics than "too many attempts" for the orphan check, but they're optional
-                if signal::killpg(Pid::from_raw(-shell_pgid.as_raw()), Signal::SIGTTIN).is_err() {
+                if signal::killpg(shell_pgid, Signal::SIGTTIN).is_err() {
                     if !interactive {
                         // that's fine
                         return;
@@ -91,7 +90,8 @@ fn take_control(interactive: bool) {
             }
         }
     }
-    if !success && interactive {
+
+    if interactive {
         eprintln!("ERROR: failed take control of the terminal, we might be orphaned");
         std::process::exit(1);
     }