Do not update nightmode from settings for car mode

- Storing is disabled, so restoration should be disabled as well.
- The old behavior is problematic in device like car as car should
  stay in night mode even if there is a user switching.

Bug: 155167849
Test: run user switching and confirm no night mode change in car
Change-Id: I03a4649ef0848d14b2af3da43178c0dfe3f26a32

services/core/java/com/android/server/UiModeManagerService.java

@@ -489,6 +489,9 @@ final class UiModeManagerService extends SystemService {
      * @return True if the new value is different from the old value. False otherwise.
      */
     private boolean updateNightModeFromSettingsLocked(Context context, Resources res, int userId) {
+        if (mCarModeEnabled) {
+            return false;
+        }
         int oldNightMode = mNightMode;
         if (mSetupWizardComplete) {
             mNightMode = Secure.getIntForUser(context.getContentResolver(),