Cgroup2: Cleanup procs in TestKill

If the test fails before we get to calling manager.Kill
we'll leak the 5 sleep processes.

Signed-off-by: Danny Canter <danny@dcantah.dev>

cgroup2/manager_test.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"syscall"
 	"testing"
 	"time"
 
@@ -153,12 +154,15 @@ func TestKill(t *testing.T) {
 	var procs []*exec.Cmd
 	for i := 0; i < 5; i++ {
 		cmd := exec.Command("sleep", "infinity")
+		// Don't leak the process if we fail to join the cg,
+		// send sigkill after tests over.
+		cmd.SysProcAttr = &syscall.SysProcAttr{
+			Pdeathsig: syscall.SIGKILL,
+		}
 		if err := cmd.Start(); err != nil {
 			t.Fatal(err)
 		}
-		if cmd.Process == nil {
-			t.Fatal("Process is nil")
-		}
+
 		if err := manager.AddProc(uint64(cmd.Process.Pid)); err != nil {
 			t.Fatal(err)
 		}