Stop flushDaemon after test run

This will prevent that running a single test fails due to a started
flushDaemon in the global logging state.

klog_test.go

@@ -42,7 +42,15 @@ import (
 // interfere with each-other.
 
 func TestMain(m *testing.M) {
-	goleak.VerifyTestMain(m)
+	exitCode := m.Run()
+	StopFlushDaemon()
+	if exitCode == 0 {
+		if err := goleak.Find(); err != nil {
+			fmt.Fprintf(os.Stderr, "goleak: %v\n", err)
+			exitCode = 1
+		}
+	}
+	os.Exit(exitCode)
 }
 
 // Test that shortHostname works as advertised.