cmd/hakurei: exec instead of fork/exec from shell

There is no reason to keep the shell process around.

Signed-off-by: Ophestra <cat@gensokyo.uk>

test/interactive/hakurei.nix

@@ -37,7 +37,7 @@
             path = "/bin/sh";
             args = [
               "-lc"
-              "sleep 1 && false"
+              "sleep 1 && exec false"
             ];
           }
         ];

test/test.py

@@ -233,6 +233,7 @@ collect_state_ui("pipewire_wayland")
 machine.send_chars("exit\n")
 machine.wait_until_fails("pgrep foot", timeout=5)
 # Test PipeWire SecurityContext:
+machine.succeed("sudo -u alice -i XDG_RUNTIME_DIR=/run/user/1000 hakurei -v run --pulse pactl info")
 machine.fail("sudo -u alice -i XDG_RUNTIME_DIR=/run/user/1000 hakurei -v run --pulse pactl set-sink-mute @DEFAULT_SINK@ toggle")
 
 # Test XWayland (foot does not support X):