Android: fix setting of system UI visibility flags

The flags were not set to the system UI with Android APIs.

Amends 58c7249ee8.

Task-number: QTBUG-118077
Change-Id: I30fb5272bdb5d7a3a3a82708b9a1604753fc4e6c
Reviewed-by: Tinja Paavoseppä <tinja.paavoseppa@qt.io>

src/android/jar/src/org/qtproject/qt/android/QtDisplayManager.java

@@ -154,6 +154,7 @@ public class QtDisplayManager {
                         WindowManager.LayoutParams.LAYOUT_IN_DISPLAY_CUTOUT_MODE_ALWAYS);
                 break;
         }
+        activity.getWindow().getDecorView().setSystemUiVisibility(systemUiVisibilityFlags);
     }
 
     public int systemUiVisibility()