Fix the multiple instences of NetworkProviderSettingsActivity issue

- Use the command "adb shell dumpsys window" to dump how many
activities/windows currently on the system.
  Then search for section like "Task display areas in top down Z order"

Bug: 191956700
Test: manual test
Use "adb shell dumpsys window" to check no more multiple instences

Change-Id: Ie9e04db3db601fbeee9beceedb81929cd6eba439

src/com/android/settings/wifi/WifiSettings.java

@@ -233,6 +233,9 @@ public class WifiSettings extends RestrictedSettingsFragment
 
         if (FeatureFlagUtils.isEnabled(getContext(), FeatureFlagUtils.SETTINGS_PROVIDER_MODEL)) {
             final Intent intent = new Intent("android.settings.NETWORK_PROVIDER_SETTINGS");
+            // Add FLAG_ACTIVITY_NEW_TASK and FLAG_ACTIVITY_CLEAR_TASK to avoid multiple
+            // instances issue. (e.g. b/191956700)
+            intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
             final Bundle extras = getActivity().getIntent().getExtras();
             if (extras != null) {
                 intent.putExtras(extras);