[Settings] Avoid from floating overlay when displaying SIM selection UI

Avoid from floating overlay when displaying SIM selection UI, which
could avoid from security issue.

Bug: 195667589
Test: local
Change-Id: I8db76005f2c3ad6cc94d68703b2b1647d81371f5

src/com/android/settings/sim/SimDialogActivity.java

@@ -24,6 +24,7 @@ import android.telecom.TelecomManager;
 import android.telephony.SubscriptionManager;
 import android.telephony.TelephonyManager;
 import android.util.Log;
+import android.view.WindowManager;
 import android.widget.Toast;
 
 import androidx.fragment.app.Fragment;
@@ -59,6 +60,8 @@ public class SimDialogActivity extends FragmentActivity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        getWindow().addSystemFlags(
+                WindowManager.LayoutParams.SYSTEM_FLAG_HIDE_NON_SYSTEM_OVERLAY_WINDOWS);
         showOrUpdateDialog();
     }