Stop creating /tmp/shim-delete-<pid> as noone uses it (#278)

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

containerd-shim/main.go

@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/signal"
 	"path/filepath"
@@ -115,7 +114,6 @@ func start(log *os.File) error {
 			}
 			// runtime has exited so the shim can also exit
 			if exitShim {
-				ioutil.WriteFile(fmt.Sprintf("/tmp/shim-delete-%d", p.pid()), []byte("deleting"), 0600)
 				p.delete()
 				p.Wait()
 				return nil