Refactor more code to use testutils.WasCalled (#13054)

* Refactor more code to use testutils.WasCalled

* incorporate review comments

* Revert watcher_test.go changes

The file is in config package and the other tests use config_test.
So it is not visible.

config/watcher_test.go

@@ -11,8 +11,6 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/require"
-
-	"github.com/mattermost/mattermost-server/utils/testutils"
 )
 
 func TestWatcherInvalidDirectory(t *testing.T) {
@@ -49,9 +47,17 @@ func TestWatcher(t *testing.T) {
 
 	// Write to a different file
 	ioutil.WriteFile(filepath.Join(tempDir, "unrelated"), []byte("data"), 0644)
-	require.False(t, testutils.WasCalled(called, 1*time.Second), "callback should not have been called for unrelated file")
+	select {
+	case <-called:
+		t.Fatal("callback should not have been called for unrelated file")
+	case <-time.After(1 * time.Second):
+	}
 
 	// Write to the watched file
 	ioutil.WriteFile(f.Name(), []byte("data"), 0644)
-	require.True(t, testutils.WasCalled(called, 5*time.Second), "callback should have been called when file written")
+	select {
+	case <-called:
+	case <-time.After(5 * time.Second):
+		t.Fatal("callback should have been called when file written")
+	}
 }