Add SIGKILL to shutdown signals (#1552)

* Add SIGKILL to shutdown signals

* go mod tidy

* Add missing file

util/signal/signal.go

@@ -0,0 +1,13 @@
+package signal
+
+import (
+	"os"
+	"syscall"
+)
+
+// ShutDownSingals returns all the singals that are being watched for to shut down services.
+func ShutdownSignals() []os.Signal {
+	return []os.Signal{
+		syscall.SIGTERM, syscall.SIGINT, syscall.SIGQUIT, syscall.SIGKILL,
+	}
+}