Revert "Add previous screen at index 0 when popping"

This reverts commit db567ea7b3.

lib/android/app/src/main/java/com/reactnativenavigation/viewcontrollers/StackController.java

                 getView().removeView(toRemove.getView());
                 listener.onSuccess(child.getId());
             }
-        } else {
-            listener.onSuccess(child.getId());
         }
     }
 
         final ViewController appearing = stack.peek();
         disappearing.onViewWillDisappear();
         appearing.onViewWillAppear();
-        getView().onChildWillDisappear(disappearing.options, appearing.options, () -> getView().addView(appearing.getView(), 0));
+        getView().onChildWillDisappear(disappearing.options, appearing.options, () ->
+                getView().addView(appearing.getView())
+        );
 
         if (disappearing.options.animated.isTrueOrUndefined()) {
             animator.pop(disappearing.getView(), () -> finishPopping(disappearing, listener));

lib/android/app/src/test/java/com/reactnativenavigation/viewcontrollers/StackControllerTest.java

     @Test
     public void push() {
         assertThat(uut.isEmpty()).isTrue();
-        CommandListenerAdapter listener = spy(new CommandListenerAdapter());
-        uut.push(child1, listener);
+        uut.push(child1, new CommandListenerAdapter());
         assertContainsOnlyId(child1.getId());
-        verify(listener, times(1)).onSuccess(child1.getId());
     }
 
     @Test
     }
 
     @Test
-    public void pop_doesNothingWhenZeroOrOneChild() {
+    public void popDoesNothingWhenZeroOrOneChild() {
         assertThat(uut.isEmpty()).isTrue();
         uut.pop(new CommandListenerAdapter());
         assertThat(uut.isEmpty()).isTrue();